GM Service Manual Online
For 1990-2009 cars only

Object Number: 550686  Size: MF
Engine Controls Components
Cruise Control, APP Module
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 the accelerator pedal position. There are 3 sensors located within the APP module that are scaled differently.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • The voltage is less than 0.25 volts on the APP 3 sensor.
    • The conditions were 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 Records.

Conditions for Clearing the MIL/DTC

    • A History DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
    • Use a scan tool in order to clear the DTCs.

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.

A scan tool reads the APP 3 position in volts. The scan tool should read approximately 4.0 volts with the throttle closed and the ignition ON or during idle. The voltage should steadily decrease as the throttle is moved toward a wide open throttle (WOT). Also, 90 percent pedal travel is acceptable for correct APP operation. Scan the APP 3 sensor while depressing the accelerator pedal with the engine stopped and the ignition ON. The display should vary from approximately 4.0 volts when the throttle is closed to approximately 2.0 volts when the throttle is held at a WOT position.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step will determine if DTC P0227 is the result of a hard failure or an intermittent condition.

  2. This step checks the PCM and the wiring.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing the DTCs, use the scan tool Capture Info function in order to save the Freeze Frame and the 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. Turn ON the ignition, with the engine OFF.
  2. With the throttle closed, observe the APP 3 voltage on the scan tool.

Is the APP 3 voltage less than or equal to the specified value?

0.25V

Go to Step 4

Go to Step 3

3

The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs are stored, refer to those tables first.

Are there any additional DTCs stored?

--

Go to the applicable DTC table

Go to Diagnostic Aids

4

  1. Disconnect the APP sensor electrical connector.
  2. Use the J 39200 DMM in order to probe the APP 3 5-volt reference circuits at the APP harness.

Is the voltage at the specified value?

5 V

Go to Step 5

Go to Step 6

5

Use the J 39200 DMM in order to probe the APP 3 signal circuit at the APP harness.

Is the APP 3 signal voltage greater than the specified value?

4.8 V

Go to Step 9

Go to Step 8

6

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

Did you perform a repair?

--

Go to Step 12

Go to Step 7

7

Check the 5-volt reference circuit for a faulty connection at the PCM and replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems.

Did you perform a repair?

--

Go to Step 12

Go to Step 11

8

  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Check the APP 3 signal circuit for a short to ground.
  4. If the APP 3 sensor signal circuit is shorted to ground, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you perform a repair?

--

Go to Step 12

Go to Step 11

9

Check for a faulty electrical connection at the APP sensor. Repair the connection as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you perform a repair?

--

Go to Step 12

Go to Step 10

10

Replace the APP module. Refer to Accelerator Pedal Position Module Replacement .

Is the action complete?

--

Go to Step 12

--

11

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

Replace the PCM.

Is the action complete?

--

Go to Step 12

--

12

  1. Use a scan tool in order to clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the normal operating temperature is reached.
  4. Select DTC and the Specific DTC function.
  5. Enter the DTC number that was set.
  6. Operate the vehicle within the Conditions for Setting this DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 13

Go to Step 2

13

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK