GM Service Manual Online
For 1990-2009 cars only

Object Number: 226926  Size: MF
Engine Controls Components L57 EFI
Engine Controls (Cell 22: Fuel Controls 5)
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to accelerator pedal position. There are three sensors located within the APP module that are scaled differently.

Conditions for Running the DTC

The ignition switch in the on position.

Conditions for Setting the DTC

    • The reference voltage on APP 2 is less than 4.8 volts.
    • All diagnostic set condition met for 2 seconds.

Action Taken When the DTC Sets

    •  The Service Throttle Soon lamp will not illuminate when one APP DTC sets. The PCM will only illuminate the Service Throttle Soon lamp when multiple APP DTCs set.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Failure Record.

Conditions for Clearing the MIL/DTC

    • A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle).
    • Use of a scan tool will clear the DTC codes.

Diagnostic Aids

There are no driveability issues associated with the APP module unless a DTC is present. The most likely cause of this DTC are poor connections or the sensor itself. The least likely is a PCM problem.

All 5 volt reference circuits must be checked for a proper reference voltage. The voltmeter accuracy is important.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

  1. This step will determine if there is a good voltage reference.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing any DTCs, use the scan tool Capture Info function to save Freeze Frame and Failure records for reference. The control module's data is deleted once the Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Disconnect the APP sensor electrical connector.
  2. Turn the ignition ON leaving the engine OFF.
  3. With J 39200 , DMM, connected to ground, check all the APP 5 volt reference circuits at the APP harness connector.

Is the voltage less than the specified value?

4.8 V

Go to Step 4

Go to Step 3

3

The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored, refer to those table(s) first.

Are additional DTC(s) stored?

--

Go to the Applicable DTC Table

Go to Diagnostic Aids

4

  1. Turn the ignition OFF.
  2. Disconnect the PCM and check the 5 volt reference circuit for a short to ground.
  3. If the 5 volt reference circuit is shorted to ground, repair it as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you perform a repair?

--

Go to Step 6

Go to Step 5

5

Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming

Replace the PCM.

Is the action complete?

--

Go to Step 6

--

6

  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the normal operating temperature is reached.
  4. Select the DTC and the Specific DTC functions.
  5. Enter the DTC number that was set.
  6. Operate the vehicle within the conditions for setting this DTC until the scan tool indicates that the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 7

Go to Step 2

7

Does the scan tool display any additional, undiagnosed DTCs?

--

Go to the Applicable DTC Table

System OK