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 powertrain control module (PCM) performs this diagnostic trouble code (DTC) diagnostic continuously. |
| • | The ignition in the ON position. |
Conditions for Setting the DTC
| • | The voltage on the APP 1 sensor is more than 4.75 volts. |
| • | All of the diagnostic set 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 poor connections or the sensor . The least likely is a PCM problem.
An intermittent may be caused by the following:
A scan tool reads the APP 1 position in volts. It should read about 0.45-0.95 volt with the throttle closed and the ignition ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward wide open throttle (WOT). Also, 90 percent pedal travel is acceptable for correct 0 APP operation. Scan the APP 1 sensor while depressing the accelerator pedal with the engine OFF and the ignition ON. The display should vary from about 0.74 volt when the throttle is closed to about 3.7 volts when the throttle is held at wide open throttle (WOT). A DTC P0123 will result if the ground circuit is open or the signal circuit is shorted to voltage.
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Electrical Intermittents in Wiring Systems.
If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems.
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 | |
Does the APP 1 measure above 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 were stored, refer to the applicable DTC tables first. Are any additional DTCs stored? | -- | Go to Diagnostic Aids | |
4 |
Does the APP 1 measure less than the specified value? | 0.25 V | Go to Step 5 | Go to Step 6 |
5 | Probe the APP 1 sensor low reference circuit at the APP sensor harness connector with an J 35616-200 Unpowered Test Light connected to battery voltage. Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 8 |
6 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
7 | Check for proper electrical connections at the APP sensor and replace the terminals if necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 |
8 |
Did you find and correct the condition? | -- | 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 DTC run and pass? | -- | Go to Step 12 | Go to Step 2 |
12 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
