FAN 4432501 - Caterpillar

Illustration 1 g02900197
Schematic of the Accelerator Pedal Position SensorThis diagnostic code is associated with the Accelerator Pedal Position Sensor. The FMI 03 means that the ECM has determined that the voltage of the circuit for the sensor is above normal. The Accelerator Pedal position control has an output frequency of approximately 500 Hz. The duty cycle of the signal changes as the Accelerator Pedal position is changed. The duty cycle increases as the Accelerator pedal is fully depressed. The Accelerator pedal values are dependent on the Accelerator pedal linkage. Valid values range from 5% to 95% duty cycle.Refer to Systems Operation, "Sensors" for more information regarding the operation of the sensor and the location.The possible causes of this diagnostic code are listed below:
The sensor power supply circuit is open.
The sensor return circuit is open.
The signal circuit is open.
The signal circuit is shorted to a voltage source.
The sensor has failed.
The ECM has failed. This is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 2795 FMI 03 is active before performing this procedure.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.System Response:The diagnostic will generate a level 2 warning. Underspeed Control will be disabled and the hystat transmission will be limited to low speed.Test Step 1. CHECK FOR POWER AT THE SENSOR.
Do not disconnect the harness connector from the sensor.
Turn the key start switch to the ON position.
At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the voltage supply wire (contact A) and return wire (contact B).
Measure the voltage from contact A to B.Expected Result:The voltage measurement is 8.0 0.5 DCV.Results:
OK - The voltage measurement is 8.0 0.5 DCV. The voltage is correct. Proceed to Test Step 2.
NOT OK - The voltage is not correct.Repair: Replace the machine harness or repair the machine harness.STOPTest Step 2. CHECK THE SIGNAL CIRCUIT FOR AN OPEN CIRCUIT.
Disconnect the negative battery cable and turn the key start switch to the OFF position.
Disconnect the machine harness from the sensor.
At the harness connector for the sensor, connect a jumper wire between contact B and contact C.
Disconnect the machine harness connector(s) from the ECM.
At the harness connector for the ECM, measure the resistance between contact J1-45 (wire P770-WH) and contact J2-24 (wire R914-OR).Expected Result:The resistance measurement is less than 5 ohms.Results:
OK - The resistance measurement is less than 5 ohms. The circuit is correct. Proceed to Test Step 3.
NOT OK - The resistance is greater than 5 ohms. The circuit is not correct. There is an open circuit in the wiring harness.Repair: Repair the wiring harness or replace the wiring harness.STOPTest Step 3. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO THE +BATTERY CIRCUIT.
The key start switch remains in the OFF position.
The machine harness remains disconnected from the sensor. Remove the jumper wire that was installed in the