P2123

DTC P2123

Circuit Description
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal control assembly. The sensor is made up of three individual sensors within one housing. The engine control module (ECM) uses the APP sensors to determine the amount of acceleration or deceleration desired by the person driving the vehicle via the fuel injector control. The APP sensor 1 has the following circuits.
- 5 volts reference circuit
- Low reference circuit
- APP sensor 1 signal circuit

The ECM supplies 5 volts to the APP sensor 1 on the 5 volts reference circuit. The ECM also provides a ground on the low reference circuit. The APP sensor 1 provides a signal to the ECM on the APP sensor 1 signal circuit, which is relative to the position changes of the accelerator pedal angle. The ECM monitors the APP sensor 1 signal for voltages outside the normal range of the APP sensor 1. If the ECM detects an excessively high APP sensor 1 signal voltage, this DTC will set.

Condition for Running the DTC
- The battery voltage is between 10-16 volts.
- The ignition switch is ON.

Condition for Setting the DTC
- The ECM detects that the APP sensor 1 signal voltage is more than 4.75 volts.

Action Taken When the DTC Sets
- The ECM does not illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

Condition for Clearing the DTC
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- Clear the DTC with a scan tool.

Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
- An open in the sensor during part of the pedal travel.
- Poor connections.
- Misrouted harness.
- Rubbed through wire insulation.
- Broken wire inside the insulation.

Check for the following conditions:
- Poor connection at ECM: Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "APP Sensor 1" display on the scan tool with the ignition ON and engine OFF while moving connectors and wiring harness related to the sensor. A change in the display will indicate the location of the fault.

DTC P2123

Schematic Reference: Engine Controls Schematics

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