DTC P1288 Accelerator Pedal Position (APP) Sensor 3 Circuit High Voltage. Generic Unit Repair 1999

For 1990-2009 cars only

Makes 🢒 Generic 🢒 1999 🢒 Unit Repair 🢒 DTC 🢒 DTC P1288 Accelerator Pedal Position (APP) Sensor 3 Circuit High Voltage

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 PCM performs this DTC diagnostic continuously.

•	DTC P1646 is not set.

Conditions for Setting the DTC

•	The signal voltage on the APP 3 sensor is greater than 4.75 volts.

•	All diagnostic conditions met for 2 seconds.

Action Taken When the DTC Sets

•	The input from APP 3 sensor is ignored.

•	This DTC will not turn on the service throttle soon lamp by itself.

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The throttle will operate normally as long as there is only one malfunction present. If two different APP sensors have a malfunction, the service throttle soon lamp will light and the PCM will limit power. If three APP sensors have a malfunction present, the service throttle soon lamp will light and the PCM will only allow the engine to operate at idle.

Conditions for Clearing the MIL/DTC

•	A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.

•	Use of a scan tool

Diagnostic Aids

Important: Remove any debris from the PCM module connector surfaces before servicing the PCM module. Inspect the PCM module connector gaskets when diagnosing/replacing the module. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM module.

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.

A scan tool reads APP 3 position in volts. Should read about 4.0 volts with throttle closed and ignition ON or at idle. Voltage should decrease at a steady rate as throttle is moved toward wide open throttle (WOT). Also, 90 percent pedal travel is acceptable for correct APP operation. Scan APP 3 sensor while depressing accelerator pedal with engine stopped and ignition ON. Display should vary from about 4.0 volts when throttle was closed to about 2.0 volts when throttle is held at wide open throttle (WOT) position.