Circuit Description
The accelerator pedal position (APP) sensor 1 and APP sensor 2 are potentiometer type sensors, each with the following circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The control module provides the APP sensors a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is also low at rest and increases as the pedal is depressed. One APP sensor DTC will not cause the Reduced Engine Power message to be displayed. Two APP sensor DTCs for the same sensor also will not cause the Reduced Engine Power message to be displayed. However, if two or more DTCs are set involving more than one APP sensor, DTC P1125 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1125 Accelerator Pedal Position (APP) System
Conditions for Running the DTC
| • | DTCs P0606, P2108, U0107 are not set. |
| • | The ignition is ON. |
| • | The communications between the throttle actuator control (TAC) module and the powertrain control module (PCM) must be valid. |
Conditions for Setting the DTC
Two APP sensors are out of range, or both APP sensors disagree with each other.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records. |
| • | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
| • | A message center or an indicator displays Reduced Engine Power. |
| • | Under certain conditions the control module commands the engine OFF. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | 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 emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Powertrain Control Module Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
This DTC indicates that 2 or more accelerator pedal position (APP) sensor DTCs are also set. Refer to the APP sensor DTCs that are set and perform those diagnostic tables. Does the scan tool display any DTCs that you have not diagnosed? | System OK | ||
