P1285

Circuit Description
The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually three individual Accelerator Pedal Position sensors within one housing. Three separate signal, ground and 5 volt reference circuits connect the Accelerator Pedal Position Sensor assembly and the Throttle Actuator Control (TAC) Module. Each sensor has a unique functionality. The APP sensor 1 signal increases as the accelerator pedal is depressed, from below 1.0 volt at 0 percent pedal travel (pedal at rest) to above 2.0 volts at 100 percent pedal travel (pedal fully depressed). The APP sensor 2 signal decreases from above 4.0 volts at 0 percent pedal travel to below 2.9 volts at 100 percent pedal travel. The APP sensor 3 signal decreases from around 3.5 volts at 0 percent pedal travel to below 3.1 volts at 100 percent pedal travel. Observe that the signal circuits for APP Sensor 2 and APP Sensor 3 pull up to 5 volts and the APP Sensor 1 signal circuit is referenced to ground within the TAC Module.

Conditions for Running the DTC
^ DTCs P0606, P1517, P1518 are not set.
^ The ignition switch is in the crank or run position.
^ The ignition voltage is greater than 5.23 volts.

Conditions for Setting the DTC
^ APP sensor 3 voltage is less than 01.63 volts or greater than 4.28 volts.
^ All above conditions met for less than 1 second.

Action Taken When the DTC Sets
^ The PCM stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
^ If no other TAC System DTCs are set, the TAC System operates normally. If certain TAC System DTCs are set at the same time, the TAC System either defaults to a Reduced Engine Power mode or to a more tightly restricted mode of operation if the TAC determines that limited safe operation is possible, or the TAC commands the engine to shut down.

Conditions for Clearing the MIL/DTC
^ A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
^ Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

Important:
^ Remove any debris from the PCM/TAC module connector surfaces before servicing the PCM/TAC module. Inspect the PCM/TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM/TAC modules.
^ For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A. Using this kit prevents damage to the harness/component terminals.
^ The following may cause an intermittent:
- Poor connections
- Corrosion
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
- Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs should set and you cannot locate any circuit or component problems.
^ The APP sensor 1 and the TP sensor 1 5.0 volt reference circuits are internally connected within the TAC module.
^ The APP sensor 2 and the TP sensor 2 5.0 volt reference circuits are internally connected within the TAC module.
^ When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
^ For an intermittent condition, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers on the diagnostic table.
7. This step is testing for a signal circuit that is shorted to a voltage.
8. This step is testing for a signal circuit that is open.
9. This step is testing for a signal circuit that is shorted to ground.
10. This step is testing for a signal circuit that is shorted to another TAC module circuit.
18. This test determines whether or not the TAC Module can recognize a change in the signal voltage.
33. When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Keep this in mind when reviewing captured DTC info.