Diagnostic Aids
APP Sensor 1 signal circuit is pulled to ground and APP Sensor 2 is pulled up to 5 volts within the ECM. APP Sensor 1 will display 0.0 volts and APP Sensor 2 will display 5.0 volts when the APP sensor electrical connector is disconnected.
The REDUCED POWER lamp will illuminate and the engine will default to the limited throttle authority limp home modes when DTC 1271 is set.
If both DTC P1275 and P1280 are set, ECM will command forced idle limp home mode.
Under certain conditions, the ECM will command the forced idle limp home mode.
Using the Scan Tool monitor APP sensor 1 and 2 voltages while varying the accelerator pedal position. For approximate readings or compare to similar known good vehicle, see ACCELERATOR PEDAL POSITION VS VOLTAGE table under DTC P1271: ACCELERATOR PEDAL POSITION SENSOR 1 TO 2 CORRELATION.
Replace accelerator pedal assembly if a problem was found.