P0123

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 tails. 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, go 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 Diagnostic Aids.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Diagnostic Aids.

TEST DESCRIPTION

Steps 1-12:

The number below refers to the step number on the diagnostic table.
2. This step determines if DTC P0123 is the result of a hard failure or an intermittent condition.