Several weird electrical problems - Traction Ctrl, AC, brake lights
05-22-2013, 12:25 AM
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Several weird electrical problems - Traction Ctrl, AC, brake lights
While I continue to browse for possible answers on this forum, I"ll go ahead and post the problems on my '97 C5. I traded a '91 Honda Accord with low miles to get this car but she's a beauty!
I do get the Service Traction Control msg. I just looked at the sticky last night. Will try to address that in next day or two.
Only my center brake light works when the brake pedal is pressed. The tail lights work but not the brake lights....only the center light. I haven't figured out which fuse it is.
A/C seems to work fine then all of a sudden the driver side gets hot but the passenger side stays cool. I have gotten in the car after it has sat for a couple hours and the A/C blows cool air from both sides again.
No codes are displayed. I did experience the dreaded Column Lock code even though my car had the recall done in 2004. The CLB did the trick.....all thanks goes to this forum!!!!!
I do get the Service Traction Control msg. I just looked at the sticky last night. Will try to address that in next day or two.
Only my center brake light works when the brake pedal is pressed. The tail lights work but not the brake lights....only the center light. I haven't figured out which fuse it is.
A/C seems to work fine then all of a sudden the driver side gets hot but the passenger side stays cool. I have gotten in the car after it has sat for a couple hours and the A/C blows cool air from both sides again.
No codes are displayed. I did experience the dreaded Column Lock code even though my car had the recall done in 2004. The CLB did the trick.....all thanks goes to this forum!!!!!
05-22-2013, 12:43 AM
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While I continue to browse for possible answers on this forum, I"ll go ahead and post the problems on my '97 C5. I traded a '91 Honda Accord with low miles to get this car but she's a beauty!
I do get the Service Traction Control msg. I just looked at the sticky last night. Will try to address that in next day or two.
Only my center brake light works when the brake pedal is pressed. The tail lights work but not the brake lights....only the center light. I haven't figured out which fuse it is.
A/C seems to work fine then all of a sudden the driver side gets hot but the passenger side stays cool. I have gotten in the car after it has sat for a couple hours and the A/C blows cool air from both sides again.
No codes are displayed. I did experience the dreaded Column Lock code even though my car had the recall done in 2004. The CLB did the trick.....all thanks goes to this forum!!!!!
I do get the Service Traction Control msg. I just looked at the sticky last night. Will try to address that in next day or two.
Only my center brake light works when the brake pedal is pressed. The tail lights work but not the brake lights....only the center light. I haven't figured out which fuse it is.
A/C seems to work fine then all of a sudden the driver side gets hot but the passenger side stays cool. I have gotten in the car after it has sat for a couple hours and the A/C blows cool air from both sides again.
No codes are displayed. I did experience the dreaded Column Lock code even though my car had the recall done in 2004. The CLB did the trick.....all thanks goes to this forum!!!!!
-Do your blinkers hyper-flash (flash quickly)? Might help diagnose the brake light problem...
-Do you have dual climate control AC? If so, the driver side getting hot is probably due to the actuator being out of sync. Again, pull the codes and post them up
Here's a link on how to pull codes from the DIC
http://www.c5forum.com/ayc/dtcdic.php
It is best that you write everything down, reset them, and drive the car for a day or so and see what comes back. Post up what you find.
05-22-2013, 12:49 AM
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-Pull the code for the traction control, it will help to diagnose.
-Do your blinkers hyper-flash (flash quickly)? Might help diagnose the brake light problem...
-Do you have dual climate control AC? If so, the driver side getting hot is probably due to the actuator being out of sync. Again, pull the codes and post them up
Here's a link on how to pull codes from the DIC
http://www.c5forum.com/ayc/dtcdic.php
It is best that you write everything down, reset them, and drive the car for a day or so and see what comes back. Post up what you find.
-Do your blinkers hyper-flash (flash quickly)? Might help diagnose the brake light problem...
-Do you have dual climate control AC? If so, the driver side getting hot is probably due to the actuator being out of sync. Again, pull the codes and post them up
Here's a link on how to pull codes from the DIC
http://www.c5forum.com/ayc/dtcdic.php
It is best that you write everything down, reset them, and drive the car for a day or so and see what comes back. Post up what you find.
I'll get those codes tomorrow. Thanks!
05-22-2013, 01:15 AM
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
HOW,,,,,,,,,,,,,,,,,,, are you reading your DTCs??????????????????
Like this:
READING YOUR Engine Diagnostic Trouble Codes (DTC)
This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.
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 ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.
Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and 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 module. ( 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 types 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. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.
If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.
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.
NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.
These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs
Here are some very good sites that explain what DTC mean:
http://www.gearchatter.com/viewtopic11755.php
http://www.obd-codes.com/trouble_cod...d-ii-codes.php
Make sure to include the H or C suffix when you post your DTCs!!
Like this:
READING YOUR Engine Diagnostic Trouble Codes (DTC)
This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.
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 ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.
Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and 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 module. ( 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 types 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. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.
If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.
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.
NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.
These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs
Here are some very good sites that explain what DTC mean:
http://www.gearchatter.com/viewtopic11755.php
http://www.obd-codes.com/trouble_cod...d-ii-codes.php
Make sure to include the H or C suffix when you post your DTCs!!
05-22-2013, 01:40 AM
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Yeah, it's hard to score one like that isn't it! I chuckle just thinking about it.
05-22-2013, 02:17 PM
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-Pull the code for the traction control, it will help to diagnose.
-Do your blinkers hyper-flash (flash quickly)? Might help diagnose the brake light problem...
-Do you have dual climate control AC? If so, the driver side getting hot is probably due to the actuator being out of sync. Again, pull the codes and post them up
Here's a link on how to pull codes from the DIC
http://www.c5forum.com/ayc/dtcdic.php
It is best that you write everything down, reset them, and drive the car for a day or so and see what comes back. Post up what you find.
-Do your blinkers hyper-flash (flash quickly)? Might help diagnose the brake light problem...
-Do you have dual climate control AC? If so, the driver side getting hot is probably due to the actuator being out of sync. Again, pull the codes and post them up
Here's a link on how to pull codes from the DIC
http://www.c5forum.com/ayc/dtcdic.php
It is best that you write everything down, reset them, and drive the car for a day or so and see what comes back. Post up what you find.
Here are the codes:
10-PCM P1571 H C
28-TCS C1277 H
99-HVAC B0361 H, B0441 H
A0-LDCM B2252 H, B2282 H, B2284 H, B2262 H, B2264 H, U1064 H, U1096 H
A1-RDCM B2253 H, B2283H, B2285H, U1064 H, U1096H
A6-SCM B0851H, B0856H, B2607H
BO-RFA U1255H, C2120H
05-22-2013, 07:38 PM
#8
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Location: Anthony TX
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
Clear ALL the DTCs and see what ones come back! Report those!
We can work from there
The HVAC DTCs are Temp Door actuator failures.
P1571
--------------------------------------------------------------------------------
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 Setting the DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
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
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
Condition intermittent, 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 setting this DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test failed?
--
Go to Step 12
Go to Step 2
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# 101551
1997 Chevrolet/Geo Corvette
========================================
--------------------------------------------------------------------------------
DTC C1277 Requested Torque Signal Circuit Malfunction
Circuit Description
Traction Control is simultaneously controlled by the EBTCM and the PCM. The PCM receives a REQUESTED TORQUE request via a Pulse Width Modulated (PWM) signal from the EBTCM requesting the desired torque level for proper Traction Control system operation. The PCM supplies the pull up voltage.
Conditions for Setting the DTC
There is an open or short in the REQUESTED TORQUE line between the EBTCM and PCM or there is a TCS communication malfunction detected by the PCM and indicated to the EBTCM, by broadcasting a PWM message.
Action Taken When the DTC Sets
A malfunction DTC is stored, the TCS is disabled and the Traction Control indicator is turned ON. ABS remains functional.
Conditions for Clearing the DTC
Condition for DTC is no longer present and scan tool clear DTC function is used.
Fifty ignition cycles have passed with no DTC(s) detected.
Diagnostic Aids
It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
If an intermittent malfunction exists refer to General Electrical Diagnosis Procedures in Wiring Systems.
Possible causes for DTC C1277 to set:
Open in CKT 463.
CKT 463 shorted to ground or voltage.
Communication frequency problem.
Communication duty cycle problem.
CKT 463 has a wiring problem, terminal corrosion, or poor connections.
PCM not receiving information from EBTCM.
Test Description
The numbers below refer to step numbers on the diagnostic table.
Checks for proper duty cycle.
Checks for proper frequency.
DTC C1277 Requested Torque Signal Circuit Malfunction Step
Action
Value(s)
Yes
No
1
Was the Diagnostic System Check performed?
--
Go to Step 2
Go to Diagnostic System Check
2
Check the following grounds, G402 and G106 making sure each ground is clean tight and free of damage. Refer to Master Electrical Component List in wiring Systems.
Were any loose, damaged, or corroded grounds found?
--
Go to Step 3
Go to Step 4
3
Repair ground as necessary. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
4
Turn the ignition switch to the OFF position.
Disconnect the EBTCM connector.
Install J 39700 Universal Pinout Box using the J 39700-25 cable adapter to the EBTCM harness connector and the EBTCM connector.
Turn the ignition switch to the ON position, engine OFF.
Using J 39200 DMM, measure the DC duty cycle between J 39700 terminals 25 and B.
Is the duty cycle within the range specified in the value(s) column?
85 - 95%
Go to Step 5
Go to Step 6
5
Using J 39200 DMM, measure the DC Hz between J 39700 terminals 25 and B.
Is the frequency within the range specified in the value(s) column?
121 - 134Hz
Go to Step 13
Go to Step 7
6
Turn the ignition switch to the OFF position.
Disconnect J 39700-25 cable adapter from the EBTCM, leaving J 39700-25 cable adapter connected to the EBTCM harness connector only.
Turn the ignition switch to the ON position, engine OFF.
Using J 39200 DMM, measure the voltage between terminals 25 and B of J 39700 .
Is the voltage within the range specified in the value(s) column?
4.5 - 5.5V
Go to Step 7
Go to Step 8
7
Replace the EBTCM. Refer to EBTCM .
Is the replacement complete?
--
Go to Diagnostic System Check
--
8
Turn the ignition switch to the OFF position.
Disconnect the PCM connector C1.
Turn the ignition switch to the ON position engine OFF.
Using J 39200 DMM, measure the voltage between terminals 25 and B of J 39700
Is the voltage within the range specified in the value(s) column?
Greater than 1V
Go to Step 9
Go to Step 10
9
Repair CKT 463 for a short to voltage. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
10
Turn the ignition switch to the OFF position.
Using J 39200 DMM, measure the resistance between J 39700 terminals 25 and B.
Is the resistance within the range specified in the value(s) column?
OL (infinite)
Go to Step 12
Go to Step 11
11
Repair CKT 463 for a short to ground. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
12
Using J 39200 DMM, measure the resistance between terminal 25 of J 39700 and the PCM connector C1 terminal 46.
Is the resistance within the range specified in the value(s) column?
0 - 2ohms
Go to Step 13
Go to Step 14
13
Replace the PCM. Refer to PCM/TAC Module Replacement in Engine Controls.
Is the diagnosis complete?
--
Go to Diagnostic System Check
--
14
Repair CKT 463 for an open. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
--------------------------------------------------------------------------------
Document ID# 172617
1997 Chevrolet/Geo Corvette
Make sure that you battery is fully charged and in good shape When you clear all the codes, I bet the others dont come back
BC
We can work from there
The HVAC DTCs are Temp Door actuator failures.
P1571
--------------------------------------------------------------------------------
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 Setting the DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
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
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
Condition intermittent, 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 setting this DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test failed?
--
Go to Step 12
Go to Step 2
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# 101551
1997 Chevrolet/Geo Corvette
========================================
--------------------------------------------------------------------------------
DTC C1277 Requested Torque Signal Circuit Malfunction
Circuit Description
Traction Control is simultaneously controlled by the EBTCM and the PCM. The PCM receives a REQUESTED TORQUE request via a Pulse Width Modulated (PWM) signal from the EBTCM requesting the desired torque level for proper Traction Control system operation. The PCM supplies the pull up voltage.
Conditions for Setting the DTC
There is an open or short in the REQUESTED TORQUE line between the EBTCM and PCM or there is a TCS communication malfunction detected by the PCM and indicated to the EBTCM, by broadcasting a PWM message.
Action Taken When the DTC Sets
A malfunction DTC is stored, the TCS is disabled and the Traction Control indicator is turned ON. ABS remains functional.
Conditions for Clearing the DTC
Condition for DTC is no longer present and scan tool clear DTC function is used.
Fifty ignition cycles have passed with no DTC(s) detected.
Diagnostic Aids
It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
If an intermittent malfunction exists refer to General Electrical Diagnosis Procedures in Wiring Systems.
Possible causes for DTC C1277 to set:
Open in CKT 463.
CKT 463 shorted to ground or voltage.
Communication frequency problem.
Communication duty cycle problem.
CKT 463 has a wiring problem, terminal corrosion, or poor connections.
PCM not receiving information from EBTCM.
Test Description
The numbers below refer to step numbers on the diagnostic table.
Checks for proper duty cycle.
Checks for proper frequency.
DTC C1277 Requested Torque Signal Circuit Malfunction Step
Action
Value(s)
Yes
No
1
Was the Diagnostic System Check performed?
--
Go to Step 2
Go to Diagnostic System Check
2
Check the following grounds, G402 and G106 making sure each ground is clean tight and free of damage. Refer to Master Electrical Component List in wiring Systems.
Were any loose, damaged, or corroded grounds found?
--
Go to Step 3
Go to Step 4
3
Repair ground as necessary. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
4
Turn the ignition switch to the OFF position.
Disconnect the EBTCM connector.
Install J 39700 Universal Pinout Box using the J 39700-25 cable adapter to the EBTCM harness connector and the EBTCM connector.
Turn the ignition switch to the ON position, engine OFF.
Using J 39200 DMM, measure the DC duty cycle between J 39700 terminals 25 and B.
Is the duty cycle within the range specified in the value(s) column?
85 - 95%
Go to Step 5
Go to Step 6
5
Using J 39200 DMM, measure the DC Hz between J 39700 terminals 25 and B.
Is the frequency within the range specified in the value(s) column?
121 - 134Hz
Go to Step 13
Go to Step 7
6
Turn the ignition switch to the OFF position.
Disconnect J 39700-25 cable adapter from the EBTCM, leaving J 39700-25 cable adapter connected to the EBTCM harness connector only.
Turn the ignition switch to the ON position, engine OFF.
Using J 39200 DMM, measure the voltage between terminals 25 and B of J 39700 .
Is the voltage within the range specified in the value(s) column?
4.5 - 5.5V
Go to Step 7
Go to Step 8
7
Replace the EBTCM. Refer to EBTCM .
Is the replacement complete?
--
Go to Diagnostic System Check
--
8
Turn the ignition switch to the OFF position.
Disconnect the PCM connector C1.
Turn the ignition switch to the ON position engine OFF.
Using J 39200 DMM, measure the voltage between terminals 25 and B of J 39700
Is the voltage within the range specified in the value(s) column?
Greater than 1V
Go to Step 9
Go to Step 10
9
Repair CKT 463 for a short to voltage. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
10
Turn the ignition switch to the OFF position.
Using J 39200 DMM, measure the resistance between J 39700 terminals 25 and B.
Is the resistance within the range specified in the value(s) column?
OL (infinite)
Go to Step 12
Go to Step 11
11
Repair CKT 463 for a short to ground. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
12
Using J 39200 DMM, measure the resistance between terminal 25 of J 39700 and the PCM connector C1 terminal 46.
Is the resistance within the range specified in the value(s) column?
0 - 2ohms
Go to Step 13
Go to Step 14
13
Replace the PCM. Refer to PCM/TAC Module Replacement in Engine Controls.
Is the diagnosis complete?
--
Go to Diagnostic System Check
--
14
Repair CKT 463 for an open. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
--
Go to Diagnostic System Check
--
--------------------------------------------------------------------------------
Document ID# 172617
1997 Chevrolet/Geo Corvette
Make sure that you battery is fully charged and in good shape When you clear all the codes, I bet the others dont come back
BC
05-23-2013, 12:54 AM
#9
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Bill, Thanks for your replies!!!! I did discover the negative battery terminal wire was not completely tightened. Maybe this coulda been some of the trouble...?....
I've read a lot of your information about the ground connectors located under the hood. What is the trick to getting those connectors apart? Until I saw your pics, I thought the other end was the one that came out.
Any thoughts why the center brake light works but not the other 2?
I've read a lot of your information about the ground connectors located under the hood. What is the trick to getting those connectors apart? Until I saw your pics, I thought the other end was the one that came out.
Any thoughts why the center brake light works but not the other 2?
05-24-2013, 11:11 PM
#10
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After resetting all the codes, here is what comes up after a day and a half of driving.
10-PCM P1571 H C
28-TCS C1277 H
99-HVAC U1064 H, U1096 H, U1160 H, and U1255 H
Drivers side AC quit working yesterday but worked fine when I cranked it up today
10-PCM P1571 H C
28-TCS C1277 H
99-HVAC U1064 H, U1096 H, U1160 H, and U1255 H
Drivers side AC quit working yesterday but worked fine when I cranked it up today
05-25-2013, 08:47 AM
#11
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
Found this bulliten but your DTC is current:
Its time to break out the Volt Meter and see if you have all the voltages discussed in the service procedure provided previously. You either dont have the 5.0 VDC reff voltage or the torque signal.
Document ID# 897646
1997 Chevrolet/Geo Corvette
--------------------------------------------------------------------------------
History DTC P1571 Stored and Will Not Clear #PI00219 - (Jul 2, 2002)
History DTC P1571 Stored and Will Not Clear
.
When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.
Condition/Concern:
Vehicle may have a DTC P1571 [ASR (Automatic Slip Regulation) Desired Torque Circuit] stored in history that cannot be cleared. DTC C1277 (Requested Torque Signal CKT Malfunction) is NOT present and there is No Service Vehicle Soon lamp or powertrain related lamps on.
Recommendation/Instructions:
This is a normal condition. All 1997 YBs will have a DTC P1571 stored as history in the PCM that cannot be cleared. If P1571 is current, follow the trouble table in SI Document Number 101551. It should be noted that the schematic in this document incorrectly lists a ckt 449 dk blu/wht and calls it Real Time Dampening. This ckt is not present and should be ignored for both 97 and 98 (Document Number 203769) model year SI. A Service Information Update has been submitted.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
© Copyright General Motors Corporation. All Rights Reserved.
--------------------------------------------------------------------------------
Document ID# 897646
1997 Chevrolet/Geo Corvette
Its time to break out the Volt Meter and see if you have all the voltages discussed in the service procedure provided previously. You either dont have the 5.0 VDC reff voltage or the torque signal.
Document ID# 897646
1997 Chevrolet/Geo Corvette
--------------------------------------------------------------------------------
History DTC P1571 Stored and Will Not Clear #PI00219 - (Jul 2, 2002)
History DTC P1571 Stored and Will Not Clear
.
When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.
Condition/Concern:
Vehicle may have a DTC P1571 [ASR (Automatic Slip Regulation) Desired Torque Circuit] stored in history that cannot be cleared. DTC C1277 (Requested Torque Signal CKT Malfunction) is NOT present and there is No Service Vehicle Soon lamp or powertrain related lamps on.
Recommendation/Instructions:
This is a normal condition. All 1997 YBs will have a DTC P1571 stored as history in the PCM that cannot be cleared. If P1571 is current, follow the trouble table in SI Document Number 101551. It should be noted that the schematic in this document incorrectly lists a ckt 449 dk blu/wht and calls it Real Time Dampening. This ckt is not present and should be ignored for both 97 and 98 (Document Number 203769) model year SI. A Service Information Update has been submitted.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
© Copyright General Motors Corporation. All Rights Reserved.
--------------------------------------------------------------------------------
Document ID# 897646
1997 Chevrolet/Geo Corvette
05-26-2013, 12:48 AM
#13
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Member Since: Apr 2007
Location: South Western Ontario
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The no brake light. Are you saying the signals and tails all work correctly but just no left and right brake lights? I would say that is the hazard switch. The brake wiring comes off the brake pedal switch and then it splits. One wire to the center brake light and the other wire to the hazard switch. There is a contact in the hazard switch it passes through and then it goes to the turn signal switch. Try cycling the hazard switch on and off a bunch of times and see if the contact clears up enough to connect so the brake lights work then you'll know for sure.
05-27-2013, 12:35 AM
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The no brake light. Are you saying the signals and tails all work correctly but just no left and right brake lights? I would say that is the hazard switch. The brake wiring comes off the brake pedal switch and then it splits. One wire to the center brake light and the other wire to the hazard switch. There is a contact in the hazard switch it passes through and then it goes to the turn signal switch. Try cycling the hazard switch on and off a bunch of times and see if the contact clears up enough to connect so the brake lights work then you'll know for sure.
