BUMPER 4494562 - Caterpillar

Illustration 2 g01288530
Inching Pedal position sensor connections
This diagnostic code is associated with the inching pedal position sensor. The FMI 08 means that the ECM has determined that the signal frequency or the signal pulse width is not within the expected range. The position sensor is a PWM sensor that operates in a frequency range of between 200 hertz to 600 hertz. The optimal operating frequency is approximately 500 hertz. The position sensor sends a PWM input signal to the Transmission/Chassis ECM. The ECM will recognize a duty cycle of 4% to 96% as valid. If the ECM detects a duty cycle that is greater than 96%, the FMI 03 diagnostic code is activated.For inching pedal operation, the Transmission/Chassis ECM is constantly running an auto calibration when the inching pedal is being used. The ECM defaults to a 20 percent duty cycle when the pedal is not depressed. The ECM defaults to a 70 percent duty cycle when the pedal is fully depressed. Using the auto calibration procedure, the ECM will adjust the acceptable pedal position limits from a possible 4 percent duty cycle when the pedal is not depressed to a possible 96 percent duty cycle when the pedal is fully depressed. Duty cycles beyond these limits will cause the ECM to activate a diagnostic code for the position sensor. The possible causes of this diagnostic code are listed below:
The sensor has failed.
Intermittent connections or poor connections in the sensor signal circuit.
The ECM has failed. This is unlikely.Note: Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected.Test Step 1. CHECK THE SIGNAL AT THE SENSORTurn the key start switch and the disconnect switch to the OFF position.
At the machine harness for the sensor connector, use a 151-6320 Removal Tool to remove the signal wire F843-YL(Yellow) and the socket at contact C from the harness connector. The machine harness connector remains connected to the connector of the inching pedal sensor.
At the back of the sensor connector, insert 7X-1710 Multimeter Probes along the sensor signal contact C and the return contact at B.
Turn the disconnect switch and the key start switch to the ON position.
Measure the frequency of the sensor signal. Measure the duty