hey guys i took my coil packs off today to clean up my valve covers and so i could paint the coil packs. i also sprayed throttle body cleaner in throttle body to cleanup the blade. and i also got MAF cleaner and i cleaned my MAF. i also washed the engine and detailed it. it will barely run now and i am throwing these codes.

PCM:
P1120-TP Sensor 1 circuit
P1220-TP Sensor 2 circuit
P1516-command vs. Actual Throttle Position Performance (TAC Module)

TCS:
C1278-TCS temporarily is inhibited by PCM

BCM:
B2723-PASS key detection circuit

any help is needed as this is my DD i think i need to clean my throttle body as it seemed to be pretty gummed up. the car runs but runs rough and if i push the gas it barely does anything. it says reduced engine power

 

Hey man,

Did you double check all your connections? Are you sure that you didn't get any water all over the traction control module down by the steering rack?

I'm not working atm so if you need a hand, shoot me a PM and I'll meet up with ya. We'll see if we can get it figured out.


Donnie

The B 2723 is most likely not related to your other issues as that is a common one.

Are these H codes or C codes?

For the heck of it, try disconnecting your battery for a bit and hook it back up.

Donnie

edit: i'll stick around and hang out til you reply, i see you're online now

 

hey donny thx. i am out of town in san jose right now visiting friends. im going to clean out the throttle body today to see if that is part of the problem

 

No prob man. Try disconnecting each one of your coil packs and re connect each one.

 

YOU WASHED THE ENGINE!!!!!: *****:

Thats the issue! read and post the DTCs that are present.

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!!








BC

 

BC,

Are you being serious about the when talking about washing the engine?

I only ask because I posted up in the general section about this same topic and a few members jumped in saying they do it all the time...just spray everything down with simple green diluted w/water and then rinse with the hose. Not covering anything in plastic at all...???

With the ground issue and such in these things, I would just worry about doing that.

I trust your opinion obviously so what say you?

Donnie

 

DOUSHING the LS engine with a hose is a BAD thing!!!! water gets in a LOT of places that causes the PCM to freak out. when I clean my engine compartment i use Wd-40 and a rag. Lots of wipeing but NO damage.

read and post your DTCs a we will get you running.

 

I agree, thanks Bill.

 

OP

Your issues tend to be associated wiyh the Throttle Position Sensor. I wuld start there. Make sure it clean and dry Replace if necessary.

BC

 

hey guys i got it fixed. i waited for everything to completely dry out and i cleaned my throttle body. that will be the last time i will wash my engine with a hose. thank you BC and donnie!

 

No prob man. Glad you got her going. Car looks good driving around too bro!

 

well thank you. you have a very nice vette as well. they almost look the same lol

 

lol, yep.

Hey man, another thing...your TP codes should be gone now?

I would give your key a good cleaning with some contact cleaner and then wipe off the little pellet with a pencil eraser. That code will probably go away(the PASS KEY one), it seems to be caused by the ignition lock cylinder itself either wearing down, breaking or a combination of these and a dirty key pellet.

 

yes all codes are gone except for the PASS key which i need to do as you described but i just havent done it. i love doing all the work myself with this car but it usually takes me awhile to get the ***** to to tear it apart as it is my DD lol. i broke my original key so i had to have one made and thats when i started getting this code. hmmm

 

also i read your profile and i see you have LT's. how do you get away with those here in cali? do u just take them off every 2 years for smog?

 

yeah, i take them off


....pm sent

 

OK Bill, Lets just say you do doush the motor like you've done 27 times before without issue, but this time it goes into reduced power, service traction control and you throw codes

P1220
P1221


And lets say you reset the codes, Unplugged the battery for and hour an had a fan blowing on the motor for a couple hours.

The car starts right up, idles great for 5 minutes, then just dies and the two codes come back...............and your wife comes into the garage and is laughing at your fustration

If it was me, and I blew out the TPS, MAF, MAP sensors and left it unplugged overnight, will it dry up and work in the morning

.............lets just say the engine is as clean as a diamond:o

 

PHIL

Your wife and my wife must know each other and plan humiliation events.

If it were ME,,,,, I would take the TPS off the TB and put it somewhere that was warm and dry for a day and see if that will dry out the sensor. From the DTCs it could be wet/damp.

If its not wet/damp inside, its bad OR the wiring at the connector is damp/wet or damaged. Carefully inspect the connector for water or damage. Use WD-40 on the connector and blow it out with compressed air.

See if that helps.

PM me if necessary.

BC

DTC P1220 Throttle Position (TP) Sensor 2 Circuit
Refer to Cell 20: TP and APP Sensors for complete circuit details.

Circuit Description
The throttle position (TP) sensor is mounted on the throttle body assembly. The sensor is actually two individual TP sensors within one housing. Two separate signal, ground and 5 volt reference circuits are used to connect the TP sensor assembly and the throttle actuator control (TAC) Module. The 2 sensors have opposite functionality. The TP sensor 1 signal voltage increases as the throttle opens, from below 1.0 volt at 0 percent throttle to above 3.5 volts at 100 percent throttle. The TP sensor 2 signal voltage decreases from around 3.8 volt at 0 percent throttle to below 1.0 volt at 100 percent throttle. Observe also that the signal circuit for TP Sensor 1 is pulled up to 5 volts and that the signal circuit for TP Sensor 2 is referenced to ground within the TAC Module.

Conditions for Running the DTC
DTCs P0606, P1517, P1518 are not set.
The ignition switch in the crank or run position.
The ignition voltage is greater than 5.23 volts.
Conditions for Setting the DTC
The TP sensor 2 voltage is less than 0.13 volts or greater than 4.87 volts.
All above conditions met for less than 1 second.
Action Taken When the DTC Sets
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
The TAC system operates in reduced engine power mode. If certain TAC system DTCs are set at the same time, the TAC system may command the engine to shut down.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL and the 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.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs should be set and no circuit or component conditions can be located.
The APP sensor 1 and the TP sensor 1 5.0 volt reference circuits are internally connected within the TAC module.
The APP sensor 2 and the TP sensor 2 5.0 volt reference circuits are internally connected within the TAC module.
When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
For an intermittent, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.

Disconnect the Throttle Actuator connector before inserting fingers into the throttle bore. Re-install the air inlet duct after repairs are completed.

The sensor voltage should drop to zero when you disconnect the sensor.

Using a test lamp reduces the amount of current fed into the signal circuit. The scan tool should display the maximum value for this parameter (5 volts) even though the actual voltage is higher.

This step is testing for a short to voltage on the TP 2 sensor signal circuit.

This step is testing for a short to voltage on the APP sensor 2 signal circuit.

The TP sensor 2 and the APP sensor 2 share a common 5 volt reference. A short to voltage on the APP sensor 2 signal circuit will affect the 5 volt reference circuit.

This step is testing for a short to voltage on the TP sensor 2 5.0 volt reference circuit.

The TP 2 sensor and the APP 2 sensor share a common 5 volt reference. The 5 volt reference circuits are connected internally within the TAC module. Disconnecting the TAC module will isolate the 5 volt reference circuits.

This step is testing for a short to voltage on the APP sensor 2 5.0 volt reference circuit.

The TP sensor 2 and the APP sensor 2 share a common 5 volt reference. A short to voltage on the APP sensor 2 5 volt reference circuit will affect the TP sensor 2 5 volt reference circuit.

This step is testing for an open TP sensor 2 5 volt reference circuit.

The TP sensor 2 5 volt reference circuit is shorted to ground if the DMM indicates continuity.

The APP sensor 2 5 volt reference circuit is shorted to ground if the DMM indicates continuity.

When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

DTC P1220 - Throttle Position (TP) Sensor 2 Circuit Step
Action
Values
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
Is DTC P1515, P1516, or P1518 also set?
--
Go to Diagnostic Trouble Code (DTC) List/Type
Go to Step 3

3
Remove the air inlet duct from the Throttle Body Assembly.

Important
Disconnecting the throttle actuator motor connector causes additional DTCs to set.


Disconnect the Throttle Actuator harness connector.
Close the throttle blade completely by hand while observing the TP sensor 2 voltage on the scan tool.
Is the voltage within the specified range?
4.3-4.8V
Go to Step 4
Go to Step 7

4
Open the throttle blade to wide open throttle (WOT) by hand while observing the TP sensor 2 voltage on the scan tool.

Is the voltage within the specified range?
0.13-1V
Go to Step 5
Go to Step 7

5
Reconnect the Throttle Actuator harness connector.
Turn OFF the ignition for 15 seconds.
Turn ON the ignition leaving the engine OFF.
Select the Diagnostic Trouble Code (DTC) Information option using the scan tool.
Move the harness and the related connectors while monitoring the DTC Information.
Does the harness movement cause this DTC to set?
--
Go to Step 25
Go to Step 6

6
Continue to monitor DTC Information using the scan tool.
Slowly depress the accelerator pedal to WOT and then slowly return it to closed throttle.
Did this DTC set?
--
Go to Step 35
Go to Diagnostic Aids

7
Monitor the TP sensor 2 voltage using a scan tool.

Is the voltage near the specified value?
5V
Go to Step 8
Go to Step 11

8
Disconnect the TP sensor harness connector.

Does the scan tool indicate the specified voltage for TP sensor 2?
0V
Go to Step 9
Go to Step 12

9
Turn OFF the ignition.
Measure the resistance from the TP sensor 2 ground circuit in the TP sensor harness connector to the battery ground using the DMM .
Is the resistance within the specified range?
0-5ohms
Go to Step 10
Go to Step 33

10
Disconnect the APP sensor. Refer to Accelerator Pedal Position (APP) Sensor Replacement .
Turn ON the ignition leaving the engine OFF.
Probe the TP sensor 2 5 volt reference circuit using the DMM connected to battery ground.
Is the voltage near the specified value?
5V
Go to Step 13
Go to Step 17

11
Disconnect the TP sensor harness connector. Refer to Throttle Position (TP) Sensor Replacement .
Probe the TP sensor 2 signal circuit using the test lamp J 34142-B connected to B+.
Does the scan tool indicate the specified voltage?
5V
Go to Step 19
Go to Step 14

12
Turn OFF the ignition.
Leave the TP sensor disconnected.
Disconnect the TAC Module connector containing the TP sensor circuits. Refer to Throttle Actuator Control (TAC) Module Replacement .
Turn ON the ignition leaving the engine OFF.
Measure the voltage from the TP sensor 2 signal circuit in the TP sensor harness connector to the battery ground using the DMM .
Is any voltage present?
--
Go to Step 30
Go to Step 16

13
Turn OFF the ignition.
Disconnect the TAC Module. Refer to Throttle Actuator Control (TAC) Module Replacement .
Turn ON the ignition leaving the engine OFF.
Measure the voltage from the APP sensor 2 signal circuit at the TAC module harness connector to the battery ground using the DMM .
Is any voltage present?
--
Go to Step 24
Go to Step 22

14
Turn OFF the ignition.
Leave the TP sensor disconnected.
Disconnect the TAC Module connector containing the TP sensor circuits. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test the harness for continuity of the TP sensor 2 signal circuit using the DMM .
Does the DMM indicate continuity?
--
Go to Step 15
Go to Step 31

15
Test the harness for continuity between the TP sensor 2 signal circuit and the battery ground using the DMM .

Does the DMM indicate continuity?
--
Go to Step 32
Go to Step 16

16
Test the TAC harness for continuity between the TP sensor 2 signal circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity?
--
Go to Step 34
Go to Step 37

17
Turn OFF the ignition.
Leave the TP and the APP sensors disconnected.
Disconnect the TAC Module connector containing the TP sensor circuits. Refer to Throttle Actuator Control (TAC) Module Replacement .
Turn ON the ignition leaving the engine OFF.
Measure the voltage from the TP sensor 2 5.0 volt reference circuit in the TP sensor harness connector to the battery ground using the DMM .
Is any voltage present?
--
Go to Step 26
Go to Step 18

18
Turn OFF the ignition.
Disconnect the other TAC Module connector. Refer to Throttle Actuator Control (TAC) Module Replacement .
Turn ON the ignition leaving the engine OFF.
Measure the voltage from the APP sensor 2 5.0 volt reference circuit at the TAC module harness connector to the battery ground using the DMM .
Is any voltage present?
--
Go to Step 27
Go to Step 22

19
Turn OFF the ignition.
Disconnect the TAC Module connector containing the TP sensor circuits. Refer to Throttle Actuator Control (TAC) Module Replacement .
Turn OFF the ignition.
Test the harness continuity for the TP sensor 2 5.0 volt reference circuit using the DMM .
Is the resistance within the specified range?
0-2ohms
Go to Step 20
Go to Step 28

20
Test the harness for continuity between the TP sensor 2 5 volt reference circuit and the battery ground using the DMM .

Does the DMM indicate continuity?
--
Go to Step 29
Go to Step 21

21
Turn OFF the ignition.
Disconnect the other TAC Module connector. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test the harness for continuity between the APP sensor 2 5 volt reference circuit and the battery ground using the DMM .
Does the DMM indicate continuity?
0-2ohms
Go to Step 29
Go to Step 22

22
Test the TAC harness for continuity between the TP sensor 2 5 volt reference circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity?
--
Go to Step 34
Go to Step 23

23
Test the TAC harness for continuity between the APP sensor 2 5 volt reference circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity?
--
Go to Step 34
Go to Step 35

24
Repair the short to voltage in the APP signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

25
Repair the harness/connections as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

26
Repair the short to voltage in the TP sensor 2 5 volt reference circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

27
Repair the short to voltage in the APP sensor 5 volt reference circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

28
Repair the open/high resistance in the 5 volt reference circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

29
Repair the short to ground in the 5.0 volt reference circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

30
Repair the signal circuit shorted to voltage. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

31
Repair the open/high resistance in the signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

32
Repair the short to ground in the signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

33
Repair the open/high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 39
--

34
Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 39
--

35
Inspect for poor connections/terminal tension at the TP sensor harness connector. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
If you find a poor connection repair the condition as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 39
Go to Step 36

36
Replace the TP sensor. Refer to Throttle Position (TP) Sensor Replacement .

Is the action complete?
--
Go to Step 39
--

37
Inspect for poor connections/terminal tension at the TAC Module harness connector. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
If you find a poor connection repair the condition as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 39
Go to Step 38

38
Replace the TAC Module. Refer to Throttle Actuator Control (TAC) Module Replacement .

Is the action complete?
--
Go to Step 39
--

39
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Start the engine and idle 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 the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this diagnostic ran and passed?
--
Go to Step 40
Go to Step 2

40
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 the applicable DTC table
System OK



--------------------------------------------------------------------------------
Document ID# 554676
2000 Chevrolet/Geo Corvette


DTC P1221 Throttle Position (TP) Sensor 1- 2 Correlation
Refer to Cell 20: TP and APP Sensors for complete circuit details.

Circuit Description
The throttle position (TP) sensor is mounted on the throttle body assembly . The sensor is actually 2 individual TP sensors within one housing. Two separate signal, ground and 5 volt reference circuits are used to connect the TP sensor assembly and the throttle actuator control (TAC) Module. The two sensors have opposite functionality. The TP sensor 1 signal voltage increases as the throttle opens, from below 1.0 volt at 0 percent throttle to above 3.5 volts at 100 percent throttle. The TP sensor 2 signal voltage decreases from around 3.8 volts at 0 percent throttle to below 1.0 volt at 100 percent throttle. Observe also that the signal circuit for TP sensor 1 is pulled up to 5 volts and that the signal circuit for TP Sensor 2 is pulled to ground within the TAC module.

Conditions for Running the DTC
DTCs P0606, P1517, P1518 not set.
Ignition switch in the crank or run position.
Ignition voltage greater than 5.23 volts.
Conditions for Setting the DTC
TP sensor 2 disagrees with TP sensor 1 by more than 7.5 percent.
All above conditions met for less than 1 second.
Action Taken When the DTC Sets
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
If no other TAC System DTCs are set, the TAC System operates in Reduced Engine Power mode. If certain TAC System DTCs are set at the same time, the TAC System either defaults to a more tightly restricted mode of operation if the TAC determines that limited safe operation is possible, or the TAC commands the engine to shut down.
The Driver Information Center displays a message.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL and the 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.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs should be set and no circuit or component conditions can be located.
The APP sensor 1 and the TP sensor 1 5.0 volt reference circuits are internally connected within the TAC module.
The APP sensor 2 and the TP sensor 2 5.0 volt reference circuits are internally connected within the TAC module.
When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
For an intermittent, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.

Disconnect the Throttle Actuator connector before inserting fingers into the throttle bore. Re-install the air inlet duct after repairs are completed.

This step determines what TP sensor circuit caused the DTC.

This step tests the TP sensor 1 5.0 volt reference circuit for high resistance. The TP sensor 2 voltage should display 5.0 volts when you jumper the two circuits together. Observe, the use of TP sensor 2 signal is only for diagnosing the TP sensor 1 5.0 volt reference circuit.

This step tests the TP sensor 1 signal and ground circuit.

This step verifies the TP sensor 1 signal circuit. The voltage should go to 0 volts when grounded. Inspect the signal circuit for high resistance if the voltage does not go to 0 volts.

This step tests the TP sensor 2 5.0 volt reference circuit for high resistance. The TP sensor 2 voltage should display 5.0 volts when you jumper the two circuits together.

This step tests for the TP sensor signal circuit. The TP sensor 2 voltage should display 5.0 volts.

When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

DTC P1221 - Throttle Position (TP) Sensors 1, 2 Performance Step
Action
Values
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
If DTC P1120, P1220, P1515, P1516, and P1518 is also set, refer to applicable DTC for further diagnosis.


Turn ON the ignition leaving the engine OFF.
Monitor the TP sensors Disagree parameter using the scan tool.
Does the scan tool indicate NO?
--
Go to Step 3
Go to Step 5

3
Remove the air inlet duct from the Throttle Body Assembly.

Important
Disconnecting the throttle actuator motor connector will cause additional DTCs to set.


Disconnect the Throttle Actuator harness connector.
Open the throttle blade to wide open throttle (WOT) by hand and then return it to closed throttle. Stop briefly at approximately 25, 50, 75 and 100 percent in each direction. Monitor the Throttle Sensors Disagree parameter at each stop.
Does the scan tool change from NO to YES while rotating the throttle blade?
--
Go to Step 25
Go to Step 4

4
Reconnect the Throttle Actuator harness connector.
Turn OFF the ignition for 15 seconds.
Turn ON the ignition leaving the engine OFF.
Select the Diagnostic Trouble Code (DTC) option using the scan tool.
Move the harness and the related connectors while monitoring the DTC status.
Does the harness movement cause this DTC to set?
--
Go to Step 14
Go to Diagnostic Aids

5
Turn OFF the ignition.
Remove the air inlet duct from the Throttle Body Assembly.

Important
Disconnecting the throttle actuator motor connector causes additional DTCs to set.


Disconnect the Throttle Actuator harness connector.
Turn ON the ignition leaving the engine OFF.
Close the throttle blade completely by hand while observing the TP sensor 1 voltage on the scan tool.
Is the voltage within the specified range?
0.13-0.67V
Go to Step 9
Go to Step 6

6
Disconnect the TP sensor electrical connector.
Jumper the TP sensor 1 5 volt reference circuit to the TP sensor 2 signal circuit.
Monitor the TP sensor 2 voltage using a scan tool.
Is the TP sensor 2 voltage at the specified value?
5.0V
Go to Step 7
Go to Step 12

7
Jumper the TP sensor 1 signal circuit to the TP sensor 1 ground circuit.
Monitor the TP sensor 1 voltage using a scan tool.
Is the TP sensor 1 voltage at the specified value?
0V
Go to Step 24
Go to Step 8

8
Jumper the TP sensor 1 signal circuit to the battery ground circuit.
Monitor the TP sensor 1 voltage using a scan tool.
Is the TP sensor 1 voltage at the specified value?
0V
Go to Step 16
Go to Step 14

9
Disconnect the TP sensor electrical connector.
Jumper the TP sensor 2 5 volt reference circuit to the TP sensor 2 signal circuit.
Monitor the TP sensor 2 voltage using a scan tool.
Is the TP sensor 2 voltage at the specified value?
5V
Go to Step 11
Go to Step 10

10
Jumper the TP sensor 2 signal circuit to the TP sensor 1 5 volt reference circuit.
Monitor the TP sensor 2 voltage using a scan tool.
Is the TP sensor 2 voltage at the specified value?
5V
Go to Step 18
Go to Step 20

11
Jumper the TP sensor 1 signal circuit to the TP sensor 2 ground circuit.
Monitor the TP sensor 1 voltage using a scan tool.
Is the TP sensor 1 voltage at the specified value?
0V
Go to Step 24
Go to Step 22

12
Disconnect the TAC module harness connectors. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test for continuity of the TP sensor 5 volt reference circuit between the TP sensor and the TAC module using the DMM .
Does the DMM indicate a continuity within the specified range?
0-2ohms
Go to Step 13
Go to Step 27

13
Test for continuity at the TAC module harness between the TP sensor 1 5 volt reference circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity between any other circuit?
--
Go to Step 26
Go to Step 28

14
Disconnect the TAC module harness connectors. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test for continuity of the TP sensor 1 signal circuit between the TP sensor and the TAC module using the DMM .
Does the DMM indicate a continuity within the specified range?
0-2ohms
Go to Step 15
Go to Step 27

15
Test for continuity at the TAC module harness between the TP sensor 1 signal circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity between any other circuit?
--
Go to Step 26
Go to Step 28

16
Disconnect the TAC module harness connectors. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test for continuity of the TP sensor 1 ground circuit between the TP sensor and the TAC module using the DMM .
Does the DMM indicate a continuity within the specified range?
0-2ohms
Go to Step 17
Go to Step 27

17
Test for continuity at the TAC module harness between the TP sensor 1 ground circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity between any other circuit?
--
Go to Step 26
Go to Step 28

18
Disconnect the TAC module harness connectors. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test for continuity of the TP sensor 5 volt reference circuit between the TP sensor and the TAC module using the DMM .
Does the DMM indicate a continuity within the specified range?
0-2ohms
Go to Step 19
Go to Step 27

19
Test for continuity at the TAC module harness between the TP sensor 2 5 volt reference circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity between any other circuit?
0-2ohms
Go to Step 26
Go to Step 28

20
Disconnect the TAC module harness connectors. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test for continuity of the TP sensor 2 signal circuit between the TP sensor and the TAC module using the DMM .
Does the DMM indicate a continuity within the specified range?
0-2ohms
Go to Step 21
Go to Step 27

21
Test for continuity at the TAC module harness between the TP sensor 1 signal circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity between any other circuit?
--
Go to Step 26
Go to Step 28

22
Disconnect the TAC module harness connectors. Refer to Throttle Actuator Control (TAC) Module Replacement .
Test for continuity of the TP sensor 2 ground circuit between the TP sensor and the TAC module using the DMM .
Does the DMM indicate a continuity within the specified range?
0-2ohms
Go to Step 23
Go to Step 27

23
Test for continuity at the TAC module harness connector between the TP sensor 2 ground circuit and all other circuits in both TAC module connectors using the DMM .

Does the DMM indicate continuity between any other circuit?
--
Go to Step 26
Go to Step 28

24
Inspect for poor connections/terminal tension at the TP sensor connector. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
If you find a poor connection, repair the condition as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 30
Go to Step 25

25
Replace the TP sensor. Refer to Throttle Position (TP) Sensor Replacement .

Is the action complete?
--
Go to Step 30
--

26
Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 30
--

27
Repair the circuit with the high resistance. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 30
--

28
Inspect for poor connections/terminal tension at the TAC module connectors. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
If you find a poor connection, repair the condition as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 30
Go to Step 29

29
Replace the TAC Module. Refer to Throttle Actuator Control (TAC) Module Replacement .

Is the action complete?
--
Go to Step 30
--

30
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Start the engine and idle 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 the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this diagnostic ran and passed?
--
Go to Step 31
Go to Step 2

31
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 the applicable DTC table
System OK



--------------------------------------------------------------------------------
Document ID# 554681
2000 Chevrolet/Geo Corvette

 

I went into the hot garage and spray electric point cleaner in the connections to the sensors and left them unplugged. Il taking the boys to busch gardens in the morning, so the heat in the garage will build and Ill try it again tomorrow night..........................if it was really mine and morgan fairchild's car.

 

":..........................if it was really mine and morgan fairchild's car.[/QUOTE]"

Its past 22:00,,,,, your wife is asleep and not reading this post??? CORRECT???

You have my phone number CORRECT? If not,,, PM ME!

BC