IMPORTANT ELECTRICAL INFORMATION (Long!)
8th Gear
Joined: Apr 2013
Posts: 8
Likes: 0
Hey Bill,
My name is bill and I have a 98 conv. and it has strange electrical issues, but the main thing is it has an intermittent starting problem, sometimes it will start, sometime it wont, hot/cold doesnt make a difference, I have done the grounds cleaning, as per your post, I have done the ignition switch as per your post, there were two corroded contacts, but they are clean now switch is back in the car...same problem still exists
The problem is, I put the key in the ignition, all the dash lights up as if it is going to crank, but it may or may not crank?, it's about a 50/50 chance either way,,, also replaced the starter today with a new one as well...your thoughts?
Thanks in advance for any help you may be able to provide!
Bill
My name is bill and I have a 98 conv. and it has strange electrical issues, but the main thing is it has an intermittent starting problem, sometimes it will start, sometime it wont, hot/cold doesnt make a difference, I have done the grounds cleaning, as per your post, I have done the ignition switch as per your post, there were two corroded contacts, but they are clean now switch is back in the car...same problem still exists
The problem is, I put the key in the ignition, all the dash lights up as if it is going to crank, but it may or may not crank?, it's about a 50/50 chance either way,,, also replaced the starter today with a new one as well...your thoughts?
Thanks in advance for any help you may be able to provide!
Bill
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
1. What is the status of your SECURITY LIGHT in the IPC when the ignition switch is ON???
2. Please read and post your DTCs. Post ALL of them.. If there a lot, clear them and the very next time the car fails to start,, IMMEDIATELY without turning off the ignition, clear any messages and read and post the DTCs.
READING YOUR Engine Diagnostic Codes (DTCs)
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open etc…)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.
Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes)
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
Here is very good site of DTC definitions:
http://www.gearchatter.com
Make sure to include the H or C suffix!!
2. Please read and post your DTCs. Post ALL of them.. If there a lot, clear them and the very next time the car fails to start,, IMMEDIATELY without turning off the ignition, clear any messages and read and post the DTCs.
READING YOUR Engine Diagnostic Codes (DTCs)
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open etc…)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.
Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes)
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
Here is very good site of DTC definitions:
http://www.gearchatter.com
Make sure to include the H or C suffix!!
8th Gear
Joined: Apr 2013
Posts: 8
Likes: 0
1. What is the status of your SECURITY LIGHT in the IPC when the ignition switch is ON???
2. Please read and post your DTCs. Post ALL of them.. If there a lot, clear them and the very next time the car fails to start,, IMMEDIATELY without turning off the ignition, clear any messages and read and post the DTCs.
READING YOUR Engine Diagnostic Codes (DTCs)
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open etc…)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.
Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes)
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
Here is very good site of DTC definitions:
http://www.gearchatter.com
Make sure to include the H or C suffix!!
2. Please read and post your DTCs. Post ALL of them.. If there a lot, clear them and the very next time the car fails to start,, IMMEDIATELY without turning off the ignition, clear any messages and read and post the DTCs.
READING YOUR Engine Diagnostic Codes (DTCs)
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open etc…)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.
Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes)
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
Here is very good site of DTC definitions:
http://www.gearchatter.com
Make sure to include the H or C suffix!!
The security light is on
PCM P1571 H C
P1631 H C
40BCM B2721 H C
B2723 H
99 HVAC BO338 H C
BO361 H
BO363 H
BO441 H C
AO LDCM B2252 H
B2282 H
B2284 H
B2262 H
B2264 H
U1064 H
A1 RDCM B2252 H
B2282 H
B2284 H
B2262 H
B2264 H
U1064 H
AD LBCM B2252 H
B2282 H
B2284 H
B2262 H
B2264 H
U1064 H
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
You had that many DTCs and you CLEARED ALL the DTCs???????
Well,,,,, Heres you major issue. Car will NOT crank as long as you have a PASS KEY Error DTC!!
The resistor chip in your KEY gets read by a set of contacts inside the metal can on the end of the ignition switch lock set. If the resistor isn't read properly, the engine WILL NOT Crank. It will keep the security light ON.
Clean the key resistor pellet metal contacts with a pencil eraser and some alcohol. That may be all thats wrong.
I just helped a buddy of mine solve the exact same issue. He ended up replacing the key lock cylinder /sensor assembly and getting a lock smith to re-key the new cylinder to the old key. CLEAR ALL your DTCs and post what comes back..
Here the code definition:
DTC B2721 PASS-Key Detection Circuit
Circuit Description
Inserting the PASS-Key® (with resistor pellet) in the ignition lock cylinder completes the PASS-Key® circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:
The theft deterrent relay to energize.
The steering column to unlock.
The BCM sends a message through the serial data line to the PCM to allow fuel enable processing to occur.
If the resistance value is incorrect, a malfunction is present and a DTC will set.
Conditions for Setting the DTC
The resistance level sampled at the BCMs PASS-Key® input circuit is one of fourteen valid but incorrect resistance ranges, signaling an invalid PASS-Key® detection.
This condition must be present for 1 second.
Action Taken When the DTC Sets
Stores a DTC B2721 in the BCM memory.
Sends a message to the IPC to display the SECURITY indicator.
The BCM will disable the theft deterrent relay.
The PCM will not allow fuel enable processing to occur.
Disables sampling of the PASS-Key® resistance for a time-out period of 3 minutes.
Does not disarm an armed UTD system.
The steering column remains in the locked position.
Conditions for Clearing the DTC
This DTC requires an ignition cycle in order to change from current to history.
The BCM detects a valid PASS-Key® resistance value on the PASS-Key® input circuit (CKT 1073).
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the IPC clearing DTCs feature.
Use a scan tool.
Diagnostic Aids
The following conditions may cause an intermittent malfunction:
There is an intermittent open or short to ground on CKT 1073 or CKT 1074.
There are poor connections at the BCM or the ignition switch connector.
The PASS-Key® is incorrect.
The ignition lock cylinder key contacts or the PASS-Key® resistor is dirty or loose.
If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. This state will last about 3 minutes. If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes. Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has lapsed.
While very unlikely, it is possible that extremely hot or cold ambient conditions may cause a DTC B2721 to set. To eliminate this possibility, perform the tests when the vehicle and the key are at room temperature. Clean the key resistor contacts of any foreign material. The foreign material could interfere with the key detection circuit and set a DTC.
Check for poor connections at the BCM and at the ignition lock cylinder. A poor connection could cause an open, an incorrect PASS-Key® resistance, or an intermittent malfunction.
If the DTC is a history DTC, the problem may be intermittent. Perform the tests while moving the related wiring, the connectors, and the key. This can often cause the malfunction to appear. Refer to Intermittents and Poor Connections .
Test Description
The numbers below refer to the step numbers on the diagnostic table:
This step checks to see if both ignition keys supplied with the vehicle are within the allowable range.
This step checks to see if an ignition lock cylinder was recently replaced. If replaced, the new PASS-Key® must be the of the same resistance value as the original PASS-Key®. If the original PASS-Key® resistance value is not available, then the PASS-Key® system may be reprogrammed. Refer to Body Control Module (BCM) Programming/RPO Configuration .
This steps checks to see if other PASS-Key® DTCs are stored; the conditions that set these DTCs could cause a DTC B2721 to set.
This step uses the ignition lock cylinder test in order to determine if the ignition lock cylinder is functioning properly.
This step determines if the BCM output voltage circuit and internal ground are good.
This step checks for an intermittent malfunction and requests a thorough inspection of any related PASS-Key® circuit wiring and connections.
DTC B2721 -- PASS-Key® Detection Circuit Out of Range Step
Action
Value(s)
Yes
No
1
Were you sent here from the BCM Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - Body Control System
2
Try each of the keys provided with the vehicle in the ignition lock cylinder, waiting 3 minutes between each in order to allow the PASS-Key® timer sequence to reset.
Does one of the keys work?
--
Go to Step 8
Go to Step 3
3
Was the ignition lock cylinder recently replaced?
--
Go to Body Control Module (BCM) Programming/RPO Configuration
Go to Step 4
4
Using a scan tool, check for PASS-Key® DTCs B2722, B2723, or B2735.
Are any of these DTCs stored in the BCM memory?
--
Go to Applicable DTC Table
Go to Step 5
5
Perform the lock cylinder test using the J 35628-A interrogator. Refer to Ignition Lock Cylinder Test .
Was a problem found?
--
Go to Step 10
Go to Step 6
6
Turn OFF the ignition switch.
Disconnect the ignition lock cylinder connector C3.
Turn ON the ignition switch.
At the BCM side of the ignition lock cylinder connector C3, measure the voltage between terminals A and B.
Is the voltage reading within specifications?
Approx. 5.0 V
Go to Step 7
Go to Step 9
7
Turn OFF the ignition switch.
Reconnect or install any connectors or components that were disconnected or removed.
Turn ON the ignition switch.
Clear any DTCs. Refer to Clearing DTCs .
Wait 5 seconds and check for DTCs.
Does DTC B2721 set as current?
--
Go to Step 11
System OK
8
Replace the malfunctioning ignition key.
Is the replacement complete?
--
Go to Step 12
--
9
Check for an open or short (to ground or voltage) in CKT 1073 or CKT 1074.
Was a problem found and repaired?
--
Go to Step 12
Go to Step 10
10
Replace the ignition lock cylinder. Refer to Ignition Switch Lock Cylinder Replacement in Instrument Panel, Gauges and Console.
Is the replacement complete?
--
Go to Step 12
--
11
Replace the BCM. Refer to Body Control Module Replacement .
Program the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration .
Is the replacement complete?
--
Go to Step 12
--
12
Turn OFF the ignition switch.
Reconnect or install any connectors or components that were disconnected or removed.
Turn ON the ignition switch.
Clear any DTCs. Refer to Clearing DTCs .
Is the repair complete?
--
Go to Diagnostic System Check - Body Control System
--
--------------------------------------------------------------------------------
Document ID# 221086
1998 Chevrolet/Geo Corvette
Well,,,,, Heres you major issue. Car will NOT crank as long as you have a PASS KEY Error DTC!!
The resistor chip in your KEY gets read by a set of contacts inside the metal can on the end of the ignition switch lock set. If the resistor isn't read properly, the engine WILL NOT Crank. It will keep the security light ON.
Clean the key resistor pellet metal contacts with a pencil eraser and some alcohol. That may be all thats wrong.
I just helped a buddy of mine solve the exact same issue. He ended up replacing the key lock cylinder /sensor assembly and getting a lock smith to re-key the new cylinder to the old key. CLEAR ALL your DTCs and post what comes back..
Here the code definition:
DTC B2721 PASS-Key Detection Circuit
Circuit Description
Inserting the PASS-Key® (with resistor pellet) in the ignition lock cylinder completes the PASS-Key® circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:
The theft deterrent relay to energize.
The steering column to unlock.
The BCM sends a message through the serial data line to the PCM to allow fuel enable processing to occur.
If the resistance value is incorrect, a malfunction is present and a DTC will set.
Conditions for Setting the DTC
The resistance level sampled at the BCMs PASS-Key® input circuit is one of fourteen valid but incorrect resistance ranges, signaling an invalid PASS-Key® detection.
This condition must be present for 1 second.
Action Taken When the DTC Sets
Stores a DTC B2721 in the BCM memory.
Sends a message to the IPC to display the SECURITY indicator.
The BCM will disable the theft deterrent relay.
The PCM will not allow fuel enable processing to occur.
Disables sampling of the PASS-Key® resistance for a time-out period of 3 minutes.
Does not disarm an armed UTD system.
The steering column remains in the locked position.
Conditions for Clearing the DTC
This DTC requires an ignition cycle in order to change from current to history.
The BCM detects a valid PASS-Key® resistance value on the PASS-Key® input circuit (CKT 1073).
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the IPC clearing DTCs feature.
Use a scan tool.
Diagnostic Aids
The following conditions may cause an intermittent malfunction:
There is an intermittent open or short to ground on CKT 1073 or CKT 1074.
There are poor connections at the BCM or the ignition switch connector.
The PASS-Key® is incorrect.
The ignition lock cylinder key contacts or the PASS-Key® resistor is dirty or loose.
If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. This state will last about 3 minutes. If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes. Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has lapsed.
While very unlikely, it is possible that extremely hot or cold ambient conditions may cause a DTC B2721 to set. To eliminate this possibility, perform the tests when the vehicle and the key are at room temperature. Clean the key resistor contacts of any foreign material. The foreign material could interfere with the key detection circuit and set a DTC.
Check for poor connections at the BCM and at the ignition lock cylinder. A poor connection could cause an open, an incorrect PASS-Key® resistance, or an intermittent malfunction.
If the DTC is a history DTC, the problem may be intermittent. Perform the tests while moving the related wiring, the connectors, and the key. This can often cause the malfunction to appear. Refer to Intermittents and Poor Connections .
Test Description
The numbers below refer to the step numbers on the diagnostic table:
This step checks to see if both ignition keys supplied with the vehicle are within the allowable range.
This step checks to see if an ignition lock cylinder was recently replaced. If replaced, the new PASS-Key® must be the of the same resistance value as the original PASS-Key®. If the original PASS-Key® resistance value is not available, then the PASS-Key® system may be reprogrammed. Refer to Body Control Module (BCM) Programming/RPO Configuration .
This steps checks to see if other PASS-Key® DTCs are stored; the conditions that set these DTCs could cause a DTC B2721 to set.
This step uses the ignition lock cylinder test in order to determine if the ignition lock cylinder is functioning properly.
This step determines if the BCM output voltage circuit and internal ground are good.
This step checks for an intermittent malfunction and requests a thorough inspection of any related PASS-Key® circuit wiring and connections.
DTC B2721 -- PASS-Key® Detection Circuit Out of Range Step
Action
Value(s)
Yes
No
1
Were you sent here from the BCM Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - Body Control System
2
Try each of the keys provided with the vehicle in the ignition lock cylinder, waiting 3 minutes between each in order to allow the PASS-Key® timer sequence to reset.
Does one of the keys work?
--
Go to Step 8
Go to Step 3
3
Was the ignition lock cylinder recently replaced?
--
Go to Body Control Module (BCM) Programming/RPO Configuration
Go to Step 4
4
Using a scan tool, check for PASS-Key® DTCs B2722, B2723, or B2735.
Are any of these DTCs stored in the BCM memory?
--
Go to Applicable DTC Table
Go to Step 5
5
Perform the lock cylinder test using the J 35628-A interrogator. Refer to Ignition Lock Cylinder Test .
Was a problem found?
--
Go to Step 10
Go to Step 6
6
Turn OFF the ignition switch.
Disconnect the ignition lock cylinder connector C3.
Turn ON the ignition switch.
At the BCM side of the ignition lock cylinder connector C3, measure the voltage between terminals A and B.
Is the voltage reading within specifications?
Approx. 5.0 V
Go to Step 7
Go to Step 9
7
Turn OFF the ignition switch.
Reconnect or install any connectors or components that were disconnected or removed.
Turn ON the ignition switch.
Clear any DTCs. Refer to Clearing DTCs .
Wait 5 seconds and check for DTCs.
Does DTC B2721 set as current?
--
Go to Step 11
System OK
8
Replace the malfunctioning ignition key.
Is the replacement complete?
--
Go to Step 12
--
9
Check for an open or short (to ground or voltage) in CKT 1073 or CKT 1074.
Was a problem found and repaired?
--
Go to Step 12
Go to Step 10
10
Replace the ignition lock cylinder. Refer to Ignition Switch Lock Cylinder Replacement in Instrument Panel, Gauges and Console.
Is the replacement complete?
--
Go to Step 12
--
11
Replace the BCM. Refer to Body Control Module Replacement .
Program the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration .
Is the replacement complete?
--
Go to Step 12
--
12
Turn OFF the ignition switch.
Reconnect or install any connectors or components that were disconnected or removed.
Turn ON the ignition switch.
Clear any DTCs. Refer to Clearing DTCs .
Is the repair complete?
--
Go to Diagnostic System Check - Body Control System
--
--------------------------------------------------------------------------------
Document ID# 221086
1998 Chevrolet/Geo Corvette
8th Gear
Joined: Apr 2013
Posts: 8
Likes: 0
Bill, first, how do i clean the contact point on the passcode
And second, I have had the car almost a year, and the security light has stayed on way more than it has stayed off!, and up until about three weeks ago it has always cranked and run just fine!... i will clean the points just need to know how and we will see what happens!
Thank you so much for your help!
Bill
And second, I have had the car almost a year, and the security light has stayed on way more than it has stayed off!, and up until about three weeks ago it has always cranked and run just fine!... i will clean the points just need to know how and we will see what happens!
Thank you so much for your help!
Bill
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Please re read my post again. "Clean the key resistor pellet metal contacts with a pencil eraser and some alcohol. That may be all thats wrong."
If you clean the contacts on the KEY and it still has the same issue, you can try to spray some switch contact cleaner inside the ignition switch lock hole.
If that doesnt work, it may be time for a NEW ignition switch lock set with a sensor on it.
If you clean the contacts on the KEY and it still has the same issue, you can try to spray some switch contact cleaner inside the ignition switch lock hole.
If that doesnt work, it may be time for a NEW ignition switch lock set with a sensor on it.
8th Gear
Joined: Apr 2013
Posts: 8
Likes: 0
Bill after I responded to the last message, i went back down to the car, the ignition switch is still out, I pulled the key cylinder out an actual removed the passkey reader off the end of it, I used a very small screw driver that i bent at the end to get in there and pull the contact switches out a bit to put more pressure on the passkey, I put it all back together, it cranked four times and then it didnt for five more trys..... I then cleared all the codes in the computer using the buttons on the dash, I have tried cranking it 10 more times and it has cranked every time!....it seems that clearing the previous codes may have helped, ?..Im not sure....however, there are 4 more current codes that have popped up,
they are pcm p1571 c
p1644 c
hvac bo338 c
bo441 c
any thoughts?
thank you again!
Bill
they are pcm p1571 c
p1644 c
hvac bo338 c
bo441 c
any thoughts?
thank you again!
Bill
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Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
For now,,, concentrate on the PCM Codes. Here are the definitions of the DTCs. Inspect the wiring and pins between the PCM and the EBTCM.. Break out your meter and see if the B+ voltages and 5VDC are where they are suppose to be.
Document ID# 203799
1998 Chevrolet/Geo Corvette
--------------------------------------------------------------------------------
DTC P1644 Traction Control Delivered Torque Output Circuit
Circuit Description
The Electronic Brake and Traction Control Module (EBTCM) supplies 12.0 Volts on the Delivered Torque circuit to the PCM. The PCM toggles this 12.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction . In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Delivered Torque signal failure. If the PCM does not receive the Delivered torque signal, this DTC sets.
Conditions for Running the DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
Conditions for Setting the DTC
The PCM does not receive the Delivered torque signal for 3 seconds.
Action Taken When the DTC Sets
The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
Conditions for Clearing the MIL/DTC
A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL/DTC.
Diagnostic Aids
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the PCM is receiving the 12.0 volts from the EBTCM.
This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.
Step
Action
Value(s)
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Important
Perform this diagnostic procedure only if the customer's concern is related to the ABS and/or the Traction Control system(s). Refer to ABS Diagnostic System Check for further diagnosis.
Verify communication between the scan tool and the EBTCM before you continue with this diagnostic. Refer to ABS Diagnostic System Check if you can not establish communications.
Turn OFF the ignition.
Install a scan tool.
Turn ON the ignition leaving the engine OFF.
Are any ABS/Traction Control DTCs set?
--
Go to applicable DTC
Go to Step 3
3
Disconnect the PCM connector located on the same side as the manufacturer's logo. Refer to PCM/TAC Module Replacement .
Turn ON the ignition leaving the engine OFF.
Probe the Delivered Torque circuit at the PCM electrical connector using the J 35616-A connector kit.
Connect the DMM J 39200 to the Delivered Torque circuit and ground.
Does the DMM display near the specified value?
B+
Go to Step 4
Go to Brakes
4
Check the terminal connections at the PCM.
If you find a connection problem, repair/replace the terminal as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 6
Go to Step 5
5
Important:
Program the replacement PCM. Refer to PCM/TAC Module Replacement .
Replace the PCM.
Is the action complete?
--
Go to Step 6
--
6
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Start engine and idle at normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test failed?
--
Go to Step 2
Go to Step 7
7
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to applicable DTC
System OK
--------------------------------------------------------------------------------
Document ID# 203799
1998 Chevrolet/Geo Corvette
Document ID# 203769
1998 Chevrolet/Geo Corvette
--------------------------------------------------------------------------------
DTC P1571 Traction Control Torque Request Circuit
Circuit Description
The PCM supplies 5.0 volts on the Desired Torque circuit to the Electronic Brake and Traction Control Module (EBTCM). The EBTCM toggles this 5.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction requested by the EBTCM. The EBTCM supplies this signal when it detects a wheel slip. In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Desired Torque signal failure. If the PCM does not receive the Desired torque signal this DTC sets.
Conditions for Running the DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
Conditions for Setting the DTC
The desired torque signal is not received by the PCM for 3 seconds.
Action Taken When the DTC Sets
The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
Conditions for Clearing the MIL/DTC
A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL/DTC.
Diagnostic Aids
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
Important
Do not perform this diagnostic procedure if the customer's concern is not related to the ABS and/or the Traction Control system(s).
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the EBTCM is receiving the 5.0 volts from the PCM. Use the connector test kit adaptor J 35616-A when probing the EBTCM connector.
If no DTCs are set, inspect connections at the EBTCM.
This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.
DTC P1571 Desired Torque Circuit Step
Action
Value(s)
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Important
Perform this diagnostic procedure only if the customer's concern is related to the ABS and/or the Traction Control system(s). Refer to ABS Diagnostic System Check for further diagnosis.
Install the scan tool.
Turn OFF the ignition.
Disconnect the EBTCM electrical connector.
Turn ON the ignition leaving the engine OFF.
Probe the Desired Torque circuit at the EBTCM electrical connector using the DMM J 39200 connected to ground.
Does the DMM display near the specified value?
5.0 V
Go to Step 3
Go to Step 4
3
Important
Verify communication between the scan tool and the EBTCM before you continue with this diagnostic. Refer to ABS Diagnostic System Check if you can not establish communications.
Are DTCs C1255 or C1277 (ABS/TCS DTCs) or B0844 (BCM DTC) set?
--
Go to Brakes or Body and Accessories for further diagnosis
Go to Diagnostic Aids
4
Probe the Desired Torque circuit at the EBTCM electrical connector using the DMM J 39200 connected to ground.
Does the DMM display near the specified value?
B+
Go to Step 7
Go to Step 5
5
Probe the Desired Torque circuit at the EBTCM electrical connector using a test lamp connected to B+.
Is the test lamp illuminated?
--
Go to Step 8
Go to Step 6
6
Check for an open in the Desired Torque circuit.
If you find a problem, repair it as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 9
7
Repair the short to B+ on the Desired Torque circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 11
--
8
Repair the short to ground on the Desired Torque circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 11
--
9
Check the terminal connections at the PCM.
If you find a problem, repair it as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 10
10
Important:
Program the replacement PCM. Refer to PCM/TAC Module Replacement .
Replace the PCM.
Is the action complete?
--
Go to Step 11
--
11
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate vehicle within the Conditions for Running this DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test failed?
--
Go to Step 2
Go to Step 12
12
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to applicable DTC
System OK
--------------------------------------------------------------------------------
Document ID# 203769
1998 Chevrolet/Geo Corvette
Document ID# 203799
1998 Chevrolet/Geo Corvette
--------------------------------------------------------------------------------
DTC P1644 Traction Control Delivered Torque Output Circuit
Circuit Description
The Electronic Brake and Traction Control Module (EBTCM) supplies 12.0 Volts on the Delivered Torque circuit to the PCM. The PCM toggles this 12.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction . In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Delivered Torque signal failure. If the PCM does not receive the Delivered torque signal, this DTC sets.
Conditions for Running the DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
Conditions for Setting the DTC
The PCM does not receive the Delivered torque signal for 3 seconds.
Action Taken When the DTC Sets
The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
Conditions for Clearing the MIL/DTC
A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL/DTC.
Diagnostic Aids
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the PCM is receiving the 12.0 volts from the EBTCM.
This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.
Step
Action
Value(s)
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Important
Perform this diagnostic procedure only if the customer's concern is related to the ABS and/or the Traction Control system(s). Refer to ABS Diagnostic System Check for further diagnosis.
Verify communication between the scan tool and the EBTCM before you continue with this diagnostic. Refer to ABS Diagnostic System Check if you can not establish communications.
Turn OFF the ignition.
Install a scan tool.
Turn ON the ignition leaving the engine OFF.
Are any ABS/Traction Control DTCs set?
--
Go to applicable DTC
Go to Step 3
3
Disconnect the PCM connector located on the same side as the manufacturer's logo. Refer to PCM/TAC Module Replacement .
Turn ON the ignition leaving the engine OFF.
Probe the Delivered Torque circuit at the PCM electrical connector using the J 35616-A connector kit.
Connect the DMM J 39200 to the Delivered Torque circuit and ground.
Does the DMM display near the specified value?
B+
Go to Step 4
Go to Brakes
4
Check the terminal connections at the PCM.
If you find a connection problem, repair/replace the terminal as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 6
Go to Step 5
5
Important:
Program the replacement PCM. Refer to PCM/TAC Module Replacement .
Replace the PCM.
Is the action complete?
--
Go to Step 6
--
6
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Start engine and idle at normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test failed?
--
Go to Step 2
Go to Step 7
7
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to applicable DTC
System OK
--------------------------------------------------------------------------------
Document ID# 203799
1998 Chevrolet/Geo Corvette
Document ID# 203769
1998 Chevrolet/Geo Corvette
--------------------------------------------------------------------------------
DTC P1571 Traction Control Torque Request Circuit
Circuit Description
The PCM supplies 5.0 volts on the Desired Torque circuit to the Electronic Brake and Traction Control Module (EBTCM). The EBTCM toggles this 5.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction requested by the EBTCM. The EBTCM supplies this signal when it detects a wheel slip. In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Desired Torque signal failure. If the PCM does not receive the Desired torque signal this DTC sets.
Conditions for Running the DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
Conditions for Setting the DTC
The desired torque signal is not received by the PCM for 3 seconds.
Action Taken When the DTC Sets
The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
Conditions for Clearing the MIL/DTC
A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL/DTC.
Diagnostic Aids
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
Important
Do not perform this diagnostic procedure if the customer's concern is not related to the ABS and/or the Traction Control system(s).
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the EBTCM is receiving the 5.0 volts from the PCM. Use the connector test kit adaptor J 35616-A when probing the EBTCM connector.
If no DTCs are set, inspect connections at the EBTCM.
This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.
DTC P1571 Desired Torque Circuit Step
Action
Value(s)
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Important
Perform this diagnostic procedure only if the customer's concern is related to the ABS and/or the Traction Control system(s). Refer to ABS Diagnostic System Check for further diagnosis.
Install the scan tool.
Turn OFF the ignition.
Disconnect the EBTCM electrical connector.
Turn ON the ignition leaving the engine OFF.
Probe the Desired Torque circuit at the EBTCM electrical connector using the DMM J 39200 connected to ground.
Does the DMM display near the specified value?
5.0 V
Go to Step 3
Go to Step 4
3
Important
Verify communication between the scan tool and the EBTCM before you continue with this diagnostic. Refer to ABS Diagnostic System Check if you can not establish communications.
Are DTCs C1255 or C1277 (ABS/TCS DTCs) or B0844 (BCM DTC) set?
--
Go to Brakes or Body and Accessories for further diagnosis
Go to Diagnostic Aids
4
Probe the Desired Torque circuit at the EBTCM electrical connector using the DMM J 39200 connected to ground.
Does the DMM display near the specified value?
B+
Go to Step 7
Go to Step 5
5
Probe the Desired Torque circuit at the EBTCM electrical connector using a test lamp connected to B+.
Is the test lamp illuminated?
--
Go to Step 8
Go to Step 6
6
Check for an open in the Desired Torque circuit.
If you find a problem, repair it as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 9
7
Repair the short to B+ on the Desired Torque circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 11
--
8
Repair the short to ground on the Desired Torque circuit. Refer to Body and Accessories/Wiring Systems.
Is the action complete?
--
Go to Step 11
--
9
Check the terminal connections at the PCM.
If you find a problem, repair it as necessary. Refer to Body and Accessories/Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 10
10
Important:
Program the replacement PCM. Refer to PCM/TAC Module Replacement .
Replace the PCM.
Is the action complete?
--
Go to Step 11
--
11
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate vehicle within the Conditions for Running this DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test failed?
--
Go to Step 2
Go to Step 12
12
Select the Capture Info option and the Review Info option using the scan tool.
Does the scan tool display any DTCs that you have not diagnosed?
--
Go to applicable DTC
System OK
--------------------------------------------------------------------------------
Document ID# 203769
1998 Chevrolet/Geo Corvette
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
You are either loosing the 5 VDC reference voltage to the sensor or the signal out of it going back to the BCM.
It could be the key losing contact inside the sensor or the circuit losing contact because of a damaged, loose or poor connection on a wire or male female pin connection some where caused by vibration during your drive.
Do you have a lot of weight hanging from or on your key??
If the PASS KEY circuit loses contact after the engine is started, the security light will come back on.
Bill
It could be the key losing contact inside the sensor or the circuit losing contact because of a damaged, loose or poor connection on a wire or male female pin connection some where caused by vibration during your drive.
Do you have a lot of weight hanging from or on your key??
If the PASS KEY circuit loses contact after the engine is started, the security light will come back on.
Bill
Advanced
Joined: Jun 2008
Posts: 56
Likes: 0
From: Saskatoon Saskatchewan
Tc1217
Set the meter up to measure DC Volts
Measure pin E to ground and you should see full battery voltage 0 Volts
Measure pin E to Pin B and you should see full battery voltage 0 Volts
Measure pin D to B and you should see full battery voltage. 11.95 Volts
D to Ground 11.95
Voltage across maxi fuse #52 11.95 Volts
I have measured and show no voltage from the two wired plugin at the maxi fuse #52 location that supplies pin E. I've found a used fuse box I'm going to see if this corrects the problem as all looks fine on the underside of the fuse box so the issue must be internal.
Measure pin E to ground and you should see full battery voltage 0 Volts
Measure pin E to Pin B and you should see full battery voltage 0 Volts
Measure pin D to B and you should see full battery voltage. 11.95 Volts
D to Ground 11.95
Voltage across maxi fuse #52 11.95 Volts
I have measured and show no voltage from the two wired plugin at the maxi fuse #52 location that supplies pin E. I've found a used fuse box I'm going to see if this corrects the problem as all looks fine on the underside of the fuse box so the issue must be internal.
Instructor
Joined: Oct 2009
Posts: 212
Likes: 4
From: Parkersburg WV
Bill, ive posted a thread about an issue im having with my 03 z06. First let me say I am short bus slow when it comes to electronics. Anyway, long story short 6 months ago car would do the pull key wait 10 sec and security light. Dealer said need new key made, so they made me one. Worked for a while id say 10 starts or so. Then the security light would just come on and stay on not every time but most of the time. Car would start fine. Then one day I got in after being in the store and car wouldn't start. Dash lights everything works just no crank. After locking and unlocking the door with the key it started. I am getting the b2721 code by the way. I cleaned the ignition "readers" with electronic cleaner didn't work. I charged battery and had it tested and read 12.7 with no load. Car has started the 3 times ive tried since charging battery. However, i get security light after about 8 miles and the b2721 code. I have a ignition/tumbler i bought off ebay. It is AC delco part. I am going to have it cut to my keys. Is this the correct step for me to take? I am at a loss, car has 36k miles by the way.
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Bill, ive posted a thread about an issue im having with my 03 z06. First let me say I am short bus slow when it comes to electronics. Anyway, long story short 6 months ago car would do the pull key wait 10 sec and security light. Dealer said need new key made, so they made me one. Worked for a while id say 10 starts or so. Then the security light would just come on and stay on not every time but most of the time. Car would start fine. Then one day I got in after being in the store and car wouldn't start. Dash lights everything works just no crank. After locking and unlocking the door with the key it started. I am getting the b2721 code by the way. I cleaned the ignition "readers" with electronic cleaner didn't work. I charged battery and had it tested and read 12.7 with no load. Car has started the 3 times ive tried since charging battery. However, i get security light after about 8 miles and the b2721 code. I have a ignition/tumbler i bought off ebay. It is AC delco part. I am going to have it cut to my keys. Is this the correct step for me to take? I am at a loss, car has 36k miles by the way.
YES,,,,,,, Its the first steps in the correct direction. Make SURE that the people doing your key /tumbler work knows that they have to do the tumbler work around a KEY with the proper RESISTANCE of your old key.
The key resistor pellet reader is on the end of the lock tumbler and that is most likely your issue. HOWEVER,,,,,,, anywhere in the PassKey circuit there could be an issue.
One way to prove out the bad key reader theory is to insert the key into the tumbler and read the resistance of the key at the connector end of the key reader connector. Compare the actual pellet resistance reading in the key with the reading you get at the connector of the key reader..
They should MATCH!!
Bill
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Well,,,,,,,,,,,,,,,,,,,,,, If you beg, borrow or find a Digital Volt / Ohm Meter, I will talk you thru the meter part. 
You dont even need to remove the ignition switch. Just remove the knee bolster and the center console and get ready to do some resistance reading
I can teach a rock how to read a meter. so you have a chance to learn a new skill!
Your BCM is set up to reconize a SPECIFIC RESISTANCE from the small resistor pelet that is contained in your key. The new key blank MUST have the same key code or same resistance.
All you need to do is order a key blank with the SAME resistor code or resistance value as your key.
You either read the value with an OHM Meter OR go to the dealer and they can look it up using your VIN.
NOTE!! You will need PROOF OF VEHICLE OWNERSHIP for them to provide you that info!
Take your key and the new ignition cylinder to the lock smith. He will repin the new cylinder to unlock with your old key and he will cut the new key and test it in the new lock cylinder.
Reinstall it and thats it.
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Bill
You dont even need to remove the ignition switch. Just remove the knee bolster and the center console and get ready to do some resistance readingI can teach a rock how to read a meter. so you have a chance to learn a new skill!
Your BCM is set up to reconize a SPECIFIC RESISTANCE from the small resistor pelet that is contained in your key. The new key blank MUST have the same key code or same resistance.
All you need to do is order a key blank with the SAME resistor code or resistance value as your key.
You either read the value with an OHM Meter OR go to the dealer and they can look it up using your VIN.
NOTE!! You will need PROOF OF VEHICLE OWNERSHIP for them to provide you that info!
Take your key and the new ignition cylinder to the lock smith. He will repin the new cylinder to unlock with your old key and he will cut the new key and test it in the new lock cylinder.
Reinstall it and thats it.
--------------------------------------------------------------------------------
Bill
Instructor
Joined: Oct 2009
Posts: 212
Likes: 4
From: Parkersburg WV
So do i need to check the new ignition or the old one? I dropped off the ignition this morning to get cut to my keys. Do i need a new key you say? Remember my key is brand new. But ill do whatever you tell me to
Instructor
Joined: Oct 2009
Posts: 212
Likes: 4
From: Parkersburg WV
Okay bill so i got my ignition back from locksmith. They want to charge me 85 bucks to install the new tumbler. Can you walk me through changing it or post a link to a how to change the tumbler? All i see is one plug. Put it in dumba&$ terms for me. Or would it be better to have them install it?
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Ill give you what the service manual has to offer:
Ignition Switch Lock Cylinder Replacement
Removal Procedure
Apply the parking brake.
Caution
Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.
Disconnect the negative battery cable.
Remove the console. Refer to Console Replacement .
Remove the IP accessory trim plate. Refer to Trim Plate Replacement - Instrument Panel (I/P) Accessory .
Remove the driver knee bolster trim panel. Refer to Trim Panel Replacement - Knee Bolster .
Remove the ignition switch lock cylinder electrical connector from the retaining tab on the side of the ignition switch.
Disconnect the ignition switch lock cylinder electrical connector.
Insert the key and turn the ignition to ON.
Using a flat bladed screwdriver or other suitable tool, depress and hold the ignition lock cylinder retaining tab (located on the RH lower side of the ignition switch)
Pull to remove the ignition lock cylinder.
Important
Take note of how the ignition switch lock cylinder wire is wrapped around the base of the ignition switch bezel.
Remove the ignition switch bezel. Carefully pull to unsnap.
Installation Procedure
Install the ignition switch bezel to the ignition switch lock cylinder.
Wrap the ignition switch lock cylinder wire around the base of the ignition switch bezel, as noted during removal.
Align the bezel slots to the lock cylinder pins, then push to secure.
Insert the ignition lock cylinder, with the key, into the ignition switch.
Press the ignition lock cylinder into place. The lock cylinder retaining tab will produce an audible click.
Check to be sure that the ignition lock cylinder is fully engaged. Use light force to pull the lock cylinder and attempt to remove it. (The lock cylinder should not be removable.)
Turn the ignition to OFF, then remove the key.
Connect the ignition switch lock cylinder electrical connector.
Install the lock cylinder electrical connector to the retaining tab on the side of the ignition switch.
Install the driver knee bolster trim panel. Refer to Trim Panel Replacement - Knee Bolster .
Install the IP accessory trim plate. Refer to Trim Plate Replacement - Instrument Panel (I/P) Accessory .
Install the console. Refer to Console Replacement .
Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Connect the negative battery. Tighten
Tighten the negative battery cable bolt to 15 N·m (11 lb ft).
Program the transmitters. Refer to Transmitter Programming in Keyless Entry.
Release the parking brake.
Inspect the functional operation of the ignition lock cylinder.
Insert the key and turn the ignition to the various positions, while checking for freedom of movement.
Attempt to remove the key while the ignition is in each of the positions. The key should only be removable in the OFF position.
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Document ID# 747223
2001 Chevrolet/Geo Corvette
I dug thru the service manual and no where does it deal with the tumbler and pins. Just lock removal from the electrical switch. That part is easy!
My buddy JUST went thru this very issue and I asked hime to save the old tumbler. I will see if he did and if I can figure out whats up with it.
Bill
Ignition Switch Lock Cylinder Replacement
Removal Procedure
Apply the parking brake.
Caution
Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.
Disconnect the negative battery cable.
Remove the console. Refer to Console Replacement .
Remove the IP accessory trim plate. Refer to Trim Plate Replacement - Instrument Panel (I/P) Accessory .
Remove the driver knee bolster trim panel. Refer to Trim Panel Replacement - Knee Bolster .
Remove the ignition switch lock cylinder electrical connector from the retaining tab on the side of the ignition switch.
Disconnect the ignition switch lock cylinder electrical connector.
Insert the key and turn the ignition to ON.
Using a flat bladed screwdriver or other suitable tool, depress and hold the ignition lock cylinder retaining tab (located on the RH lower side of the ignition switch)
Pull to remove the ignition lock cylinder.
Important
Take note of how the ignition switch lock cylinder wire is wrapped around the base of the ignition switch bezel.
Remove the ignition switch bezel. Carefully pull to unsnap.
Installation Procedure
Install the ignition switch bezel to the ignition switch lock cylinder.
Wrap the ignition switch lock cylinder wire around the base of the ignition switch bezel, as noted during removal.
Align the bezel slots to the lock cylinder pins, then push to secure.
Insert the ignition lock cylinder, with the key, into the ignition switch.
Press the ignition lock cylinder into place. The lock cylinder retaining tab will produce an audible click.
Check to be sure that the ignition lock cylinder is fully engaged. Use light force to pull the lock cylinder and attempt to remove it. (The lock cylinder should not be removable.)
Turn the ignition to OFF, then remove the key.
Connect the ignition switch lock cylinder electrical connector.
Install the lock cylinder electrical connector to the retaining tab on the side of the ignition switch.
Install the driver knee bolster trim panel. Refer to Trim Panel Replacement - Knee Bolster .
Install the IP accessory trim plate. Refer to Trim Plate Replacement - Instrument Panel (I/P) Accessory .
Install the console. Refer to Console Replacement .
Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Connect the negative battery. Tighten
Tighten the negative battery cable bolt to 15 N·m (11 lb ft).
Program the transmitters. Refer to Transmitter Programming in Keyless Entry.
Release the parking brake.
Inspect the functional operation of the ignition lock cylinder.
Insert the key and turn the ignition to the various positions, while checking for freedom of movement.
Attempt to remove the key while the ignition is in each of the positions. The key should only be removable in the OFF position.
--------------------------------------------------------------------------------
Document ID# 747223
2001 Chevrolet/Geo Corvette
I dug thru the service manual and no where does it deal with the tumbler and pins. Just lock removal from the electrical switch. That part is easy!
My buddy JUST went thru this very issue and I asked hime to save the old tumbler. I will see if he did and if I can figure out whats up with it.
Bill
Advanced
Joined: Jun 2008
Posts: 56
Likes: 0
From: Saskatoon Saskatchewan
Set the meter up to measure DC Volts
Measure pin E to ground and you should see full battery voltage 0 Volts
Measure pin E to Pin B and you should see full battery voltage 0 Volts
Measure pin D to B and you should see full battery voltage. 11.95 Volts
D to Ground 11.95
Voltage across maxi fuse #52 11.95 Volts
I have measured and show no voltage from the two wired plugin at the maxi fuse #52 location that supplies pin E. I've found a used fuse box I'm going to see if this corrects the problem as all looks fine on the underside of the fuse box so the issue must be internal.
Measure pin E to ground and you should see full battery voltage 0 Volts
Measure pin E to Pin B and you should see full battery voltage 0 Volts
Measure pin D to B and you should see full battery voltage. 11.95 Volts
D to Ground 11.95
Voltage across maxi fuse #52 11.95 Volts
I have measured and show no voltage from the two wired plugin at the maxi fuse #52 location that supplies pin E. I've found a used fuse box I'm going to see if this corrects the problem as all looks fine on the underside of the fuse box so the issue must be internal.