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 voltage is more than 6.4 volts. |
| • | The engine speed is more than 300 RPM. |
| • | There are no in range faults for APP 1 or APP 2--The powertrain control module (PCM) checks for high and low voltage faults. |
Conditions for Setting the DTC
| • | The difference between APP 3 and APP 1 is more than 0.23 volts--The PCM compares the pre-scaled voltage that is internal to the PCM. |
| • | The difference between APP 3 and APP 2 is more than 0.50 volt--The PCM compares the pre-scaled voltage that is internal to the PCM. |
| • | The conditions are met for 2 seconds. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
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 itself. The least cause likely is a PCM condition.
An intermittent may be caused by the following conditions:
| • | Faulty connections |
| • | Rubbed-through wire insulation |
| • | A broken wire inside the insulation |
A scan tool reads the APP 3 position in volts. The scan tool should read approximately 4 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 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 volts when the throttle was closed to approximately 2 volts when the throttle is held at the WOT position.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Are the APP voltages at the specified values? The values are listed as APP 1, APP 2, and APP 3 respectively. | 0.45-0.95 V 4-4.5 V 3.6-4 V | Go to Step 3 | Go to Step 4 | |
3 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs are stored, refer to the applicable DTC tables first. Are any additional DTCs stored? | -- | Go to Diagnostic Aids | |
4 |
Does the voltage measure more than or equal to the specified value on all of the circuits? | 4.75 V | Go to Step 5 | Go to Step 6 |
5 |
Is the test lamp ON for all of the circuits? | -- | Go to Step 9 | Go to Step 8 |
6 |
Did you perform a repair? | -- | Go to Step 11 | 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 11 | Go to Step 10 |
8 |
Did you perform a repair? | -- | Go to Step 11 | Go to Step 10 |
9 | Replace the APP module. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the scan tool indicate the diagnostic passed? | -- | Go to Step 12 | Go to Step 2 |
12 | Does the scan tool display any additional undiagnosed DTCs? | -- | System OK | |
