P1280

Diagnostic Chart (Part 1 Of 4):

Diagnostic Chart (Part 2 Of 4):

Diagnostic Chart (Part 3 Of 4):

Diagnostic Chart (Part 4 Of 4):

Refer to Engine Controls Schematics Control Module, Cruise Control Switch, APP Sensor

CIRCUIT DESCRIPTION
The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually 3 individual APP sensors within one housing. Three separate signal, ground, and 5.0 Volt reference circuits connect the APP 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, the pedal is at rest, to above 2.0 volts at 100 percent pedal travel, the pedal is 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 above 3.8 volts at 0 percent pedal travel to below 3.1 volts at 100 percent pedal travel. Observe that the signal circuits or 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 P0601, P0602, P0606, P1517, P1518 are not set.
^ The ignition switch is in the crank or run position.
^ The ignition voltage is more than 5.23 volts.

CONDITIONS FOR SETTING THE DTC
^ The APP sensor 2 voltage ranges between 0.83 volts and 4.81 volts
^ All of the above conditions are 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 commands the engine to operate in a reduced engine power mode. The TAC system may command the engine to shut down.

CONDITIONS FOR CLEARING THE DTC
^ A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
^ A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Use a scan tool in order to clear the DTC.

DIAGNOSTIC AIDS

IMPORTANT:
^ Remove any debris from the Powertrain Control Module (PCM) or TAC module connector surfaces before servicing the PCM or TAC module. Inspect the PCM or TAC module connector gaskets when diagnosing or replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM or TAC modules.
^ For any test that requires probing the PCM or a component harness connector, use the J 35616-A connector test adapter kit. Using this kit prevents damage to the harness or component terminals. Refer to Using Connector Test Adapters in Diagrams.
^ The following may cause an intermittent:
- Poor connections-Refer to Testing for Intermittent and Poor Connections in Diagrams.
- Corrosion
- Misrouted harness
- Rubbed through wire insulation
- Broken wire inside the insulation
^ Inspect the TAC module connectors for signs of water intrusion. This causes intermittent DTCs.
^ The APP sensor 1 and the TP sensor 1 5.0 Volt reference circuits are internally connected within the TAC.
^ The APP sensor 2 and the TP sensor 2 5.0 Volt reference circuits are internally connected within the TAC.
^ When the TAC module detects throttle movement with a DTC P1280 set, a DTC P1281 also sets.
^ 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 step numbers on the diagnostic table.
2. TP sensor 2 and the APP sensor 2 share a common 5.0 Volt reference source. Diagnosis DTC P1220 first, if set.
18. This test determines whether or not the TAC module can recognize a change in signal voltage.
19. There are 3 separate 5.0 Volt reference sources within the TAC module. TP sensor 1 and APP sensor 1 share one 5.0 Volt reference source, TP sensor 2 and APP sensor 2 share another common 5.0 Volt reference source, and APP sensor 3 uses the third. This test determines whether the signal circuit is shorted to any one of the 5.0 Volt reference circuits. If a short exists, the corresponding sensor voltage will be pulled low.
20. The previous step found the signal circuit and a 5.0 Volt reference circuit shorted together. This test isolates whether the short is in the harness or within the TAC module.
35. When a condition is detected 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.