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 which are 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 more than 4.75 volts on the APP 2.
    • The condition is met for 2 seconds.

Action Taken When the DTC Sets

    •  The service throttle soon lamp will not illuminate when one APP DTC sets. The powertrain control module (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 causes of this DTC are faulty connections or the sensor. The least likely cause is a PCM problem.

A scan tool reads the APP 2 position in volts and should read approximately 4.5 volts with the throttle closed and the ignition ON or at idle. The voltage should decrease at a steady rate as the throttle is moved toward wide open throttle (WOT). Also, 90 percent pedal travel is acceptable for a correct APP operation. Scan the APP 2 signal while depressing the accelerator pedal with the engine stopped and the ignition ON. The display should vary from approximately 4.5 volts when the throttle is closed to approximately 1.5 volts when the throttle is held at the WOT position. A DTC P1125 may possibly set along with DTC P0223 if the signal circuit is open.

Test Description

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

  1. This step determines if PO223 is a hard failure or an intermittent condition.

  2. This step checks for an open in the ground circuit.

  3. This step checks for a short to power or a bad APP module.

  4. This step ensures that the replacement PCM, which utilizes an electrically erasable programmable read-only memory (EEPROM), is programmed when installed.

Step

Action

Values

Yes

No

1

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

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

  1. Turn ON the ignition, leaving the engine OFF.
  2. With the throttle closed, observe the APP 2 display on the scan tool.

Is the APP 2 display more than or equal to the specified value?

4.75 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 are stored, refer to the applicable DTC tables first.

Are any additional DTCs stored?

--

Go to the applicable DTC table

Go to Diagnostic Aids

4

  1. Disconnect the APP sensor harness connector.
  2. Probe the APP 2 sensor ground circuit at the APP sensor harness connector with an unpowered test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 7

5

Use a fused jumper wire in order to jump the APP 2 signal circuit to the APP 2 ground circuit at the APP harness connector.

Does the scan tool display an APP 2 voltage less than the specified value?

0.25 V

Go to Step 8

Go to Step 6

6

  1. Check for an open on the APP 2 sensor signal circuit.
  2. If the APP 2 sensor signal circuit is open, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you perform a repair?

--

Go to Step 14

Go to Step 12

7

  1. Check for an open sensor ground circuit.
  2. If you find a problem, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you perform a repair?

--

Go to Step 14

Go to Step 12

8

  1. Verify the ignition is ON with the engine OFF.
  2. Verify the APP harness is still disconnected from the APP module.
  3. With a digital multimeter (DMM) set to the mA scale, measure the current between the APP 2 signal circuit and the ground circuit at the harness connector

Is the current more than the specified value?

30 mA

Go to Step 9

Go to Step 10

9

Repair the short to voltage on the APP 2 signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 14

--

10

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

Did you perform a repair?

--

Go to Step 14

Go to Step 11

11

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

Is the action complete?

--

Go to Step 14

--

12

  1. Check for a faulty electrical connection at the PCM.
  2. Repair the connection as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you perform a repair?

--

Go to Step 14

Go to Step 13

13

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 14

--

14

  1. Use a scan tool in order to clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches a normal operating temperature.
  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 the DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 15

Go to Step 2

15

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC tables

System OK