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 is in the ON position. |
Conditions for Setting the DTC
| • | The voltage on the APP 1 sensor is less than 0.25 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.
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 APP operation. Scan the APP sensor while depressing the accelerator pedal with the engine OFF and the ignition ON. The display should vary from about 0.74 volt when throttle is closed to about 3.7 volts when the throttle is held at wide open throttle (WOT). A DTC P0122 will result if the signal or reference circuit are open.
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 numbers below refer to the step numbers on the diagnostic table.
-
This step determines if DTC P0122 is the result of a hard failure or an intermittent condition.
-
This step checks the PCM and wiring.
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 voltage measure less than the specified value? | 0.25 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 those tables first. Are any additional DTCs stored? | -- | Go to Diagnostic Aids | |
Does the APP 1 voltage measure more than the specified value? | 4.75 V | Go to Step 10 | Go to Step 5 | |
5 |
Does the APP 1 voltage measure more than the specified value? | 4.75 V | Go to Step 8 | |
6 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 |
7 | Check the 5-volt reference circuit for a proper connection at the PCM and replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
8 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
9 | Check the APP 1 sensor signal circuit for a proper connection at the PCM and replace terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Check for a proper electrical connection at the APP module. Repair the connection if necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
11 | Replace the APP module. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 |
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
