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 PCM performs this DTC diagnostic continuously. |
| • | The ignition switch in the ON position. |
Conditions for Setting the DTC
| • | The signal voltage on the APP 3 sensor is less than 0.25 volts. |
| • | All diagnostic conditions met for 2 seconds. |
Action Taken When the DTC Sets
| • | The input from APP 3 sensor is ignored. |
| • | This DTC will not turn on the Service Throttle Soon lamp by itself. |
| • | The throttle will operate normally as long as there is only one malfunction present. If two different APP sensors have a malfunction, the Service Throttle Soon lamp will light and the PCM will limit power. If three APP sensors have a malfunction present, the Service Throttle Soon lamp will light and the PCM will only allow the engine to operate at idle. |
Conditions for Clearing the MIL/DTC
| • | A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures. |
| • | The use of 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 poor connections or the sensor itself. The least likely is a PCM problem.
A scan tool reads APP 3 position in volts. It should read about 4.0 volts with the throttle closed and the ignition ON or at idle. 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 correct APP operation. Scan APP 3 sensor while depressing the accelerator pedal with the engine off and the ignition ON. Display should vary from about 4.0 volts when the throttle is closed to about 2.0 volts when the throttle is held at wide open throttle (WOT).
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame and failure records for reference. The control modules data is deleted once the Clear Info function is used. Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Is the APP 3 voltage less than or equal to the specified value? | 0.25 V | |||
3 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored, refer to those tables first. Are any additional DTCs stored? | -- | Go to applicable DTC | Go to Diagnostic Aids |
4 |
Is the voltage at the specified value? | 5 V | ||
5 | Use DMM in order to probe the APP 3 signal circuit at the APP harness. Is the voltage at the specified value? | 4.8 V | ||
6 |
Was the 5 volt reference circuit open or shorted to ground? | -- | ||
7 | Check the 5 volt reference circuit for a proper connection at the PCM and replace terminal if necessary. Did the terminal require replacement? | -- | ||
8 |
Was the APP 3 signal circuit open or shorted to ground? | -- | ||
9 | Check the APP 3 sensor signal circuit for a proper connection at the PCM and replace terminal if necessary. Did the terminal require replacement? | -- | ||
10 | Check for a proper electrical connection at the APP sensor. Did you perform a repair? | -- | ||
11 | Replace the APP module. Refer to Accelerator Pedal Position Module Replacement . Is the action complete? | -- | -- | |
12 |
Important: The new PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
13 |
Does the scan tool indicate the diagnostic Passed? | -- | ||
14 | Does the scan tool display any additional undiagnosed DTCs? | -- | Go to applicable DTC | System OK |
