P0221

Circuit Description
The Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to accelerator position. There are three differently scaled sensors located within the APP module.

Conditions for Running the DTC
^ The ignition voltage is greater than 6.4 volts.
^ The engine speed is greater than 300 RPM.
^ There are no in range faults for APP 1 or APP 3 [Powertrain Control Module (PCM) checks for high and low voltage faults].

Conditions for Setting the DTC
^ The difference between APP 2 and APP 3 is greater than 0.50 volts [PCM compares pre-scaled voltage (internal to PCM)].
^ The difference between APP 2 and APP 1 is greater than 0.23 volts [the PCM compares the pre-scaled voltage (internal to the PCM)].
^ The conditions were 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 is stored in the Failure Records.

Conditions for Clearing the MIL/DTC
^ The PCM will turn the MIL off after three consecutive trips without a fault condition.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures
^ The 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 cause of this DTC are poor connections or the sensor itself. The least likely is a Powertrain Control Module (PCM) problem.

An intermittent may be caused by the following:
^ Poor connections
^ A rubbed through wire insulation
^ Broken wire inside the insulation

A scan tool reads the APP 2 position in volts and should read about 4.5 volts with the throttle closed and the ignition ON or at idle. The voltage should decrease at a steady rate as the throttle is moved toward Wide Open Throttle (WOT). Also, 90 percent pedal travel is acceptable for correct APP operation. Scan the APP 2 sensor while depressing the accelerator pedal with the engine stopped and the ignition ON. The display should vary from about 4.5 volts when the throttle is closed to about 1.5 volts when the throttle is held at the WOT position.

Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table.
4. This step determines if there is a good 5 volt reference.
5. This step will check for an open in the ground circuit.