P0123

Diagnostic Chart:

Wiring Diagram:

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 Setting the DTC

^ The PCM performs this DTC diagnostic continuously.

^ The voltage on the APP 1 sensor is greater than 4.75 volts.

^ All of the diagnostic set conditions met for 2 seconds.

Action Taken When the DTC Sets

^ The Service Throttle Soon lamp will not illuminate when one APP DTC sets. The PCM will only illuminate the Service Throttle Soon lamp when multiple APP DTCs set.

^ The PCM records the operating conditions at the time the diagnostic fails. This information will store in the Failure Records.

Conditions for Clearing the MIL/DTC

^ A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F)) that same ignition cycle.

^ Use of 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 itself. The least likely is a PCM problem.

An intermittent may be caused by the following:

A scan tool reads APP 1 position in volts. Should read about 0.45 to 0.95 volt with throttle closed and ignition ON or at idle. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT). Also, 90% pedal travel is acceptable for correct 0 APP operation. Scan APP 1 sensor while depressing accelerator pedal with engine stopped and ignition ON. Display should vary from about 0.74 volt when throttle was closed to about 3.7 volt when throttle is held at Wide Open Throttle (WOT) position. A P0123 will result if the ground circuit is open or the signal circuit is shorted to voltage.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

2. This step determines if DTC P0123 is the result of a hard failure or an intermittent condition.

3. This step checks the PCM and wiring.