P2123

DTC P2123

Circuit Description

The accelerator pedal assembly contains 2 accelerator pedal position (APP) sensors. The APP sensors are mounted in the pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to the position of the accelerator pedal. The engine control module (ECM) supplies a separate 5-volt reference and low reference circuit for each of the APP sensors.

The APP sensor 1 signal voltage increases as the pedal is depressed, from approximately 1.0 volt at rest to above 4 volts when fully depressed. The APP sensor 2 signal voltage increases as the pedal is depressed, from approximately 0.5 volt at rest to more than 2 volts with the accelerator pedal fully depressed.

If the ECM detects that the APP 1 signal voltage is too high, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2123 Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage

Conditions for Running the DTC

* The ignition is ON or the engine is operating.
* The ignition 1 voltage is more than 7 volts.
* DTC P2123 runs continuously once the above conditions are met.

Conditions for Setting the DTC

The APP sensor 1 voltage is more than 4.82 volts for more than 4 seconds.

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/Failure Records.

Conditions for Clearing the MIL/DTC

* The control module turns OFF the malfunction indicator lamp (MIL) after 4 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.

Diagnostic Aids

* Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
* The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views.
* For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

Test Description

Step 1 - Step 7:

Step 8 - Step 16:

The numbers below refer to the step numbers on the diagnostic table.
3. This step tests the internal circuits of the APP sensor 1 throughout its range of motion. If this DTC sets when slowly moving the pedal from the rest position to wide open throttle (WOT), replace the APP assembly for an internal fault.
7. This step tests for high resistance in the low reference circuit of the APP sensor 1. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM/TCM fuse allows the ECM to power down completely.