P1276

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% pedal travel (pedal at rest) to above 2.0 volts at 100% pedal travel (pedal fully depressed). The APP sensor 2 signal decreases from above 4.0 volts at 0% pedal travel to below 2.9 volts at 100% pedal travel. The APP sensor 3 signal decreases from around 3.8 volts at 0% pedal travel to below 3.1 volts at 100% 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 pull 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 1 disagrees with APP sensor 2 by more than 10.5% and APP sensor 1 disagrees with APP sensor3 by more than 13.0%.
^ All of the 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 the wire insulation
- Broken wire inside the insulation
- Inspect the TAC module connectors for signs of water intrusion.
^ 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.
^ For an intermittent condition, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the steps numbers in the diagnostic table
2. This step determines if a communication condition exists.
5. This step isolates an internal APP sensor failure. The condition may only occur at a certain accelerator pedal position. Monitoring the APP angles for sensor 2 and sensor 3 is an accurate way of verifying the actual position of the pedal. The APP angles for all 3 sensors should be within a few percent of each other. When the pedal is at rest the APP angle for all 3 sensors should be 0 percent, when the pedal is fully depressed all APP angles should be 100 percent.
6. The APP sensor 1 shares a common 5 volt reference circuit with the TP sensor 1. Monitoring the TP sensor 1 voltage aids in diagnosing the APP sensor 5 volt reference and ground circuits. If the scan tool displays near 0 volts then the circuits are OK.
10. This step determines whether the TAC module or a shorted circuit is causing the condition.
11. Excessive resistance in the circuit causes this DTC to set.
12. Excessive resistance in the circuit causes this DTC to set.
13. Excessive resistance in the circuit causes this DTC to set.