Conditions Which Generate This Code:
Schematic of the Throttle Position Sensor
This diagnostic code is associated with the Throttle Position Sensor. The FMI 04 means that the ECM has determined that the voltage of the circuit for the position sensor is below normal.
The throttle position control has an output frequency of approximately 500 Hz. The duty cycle of the signal changes as the throttle pedal position is changed. The duty cycle increases as the throttle pedal is depressed. The throttle pedal values are dependent on the throttle pedal linkage. Valid values range from 5% to 95% duty cycle.
The possible causes of this diagnostic code are listed below:
- Improperly adjusted throttle pedal linkage.
- The signal circuit for the sensor is shorted to ground.
- 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 0091 FMI 04 is active before performing this procedure.
Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.
The diagnostic code 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 THE OUTPUT OF THE SENSOR.
- At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the signal wire (contact C).
- At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the ground wire (contact B).
- Turn the key start switch to the ON position.
- Measure the duty cycle of the signal. The valid sensor range is 5% duty cycle to 95% duty cycle. This fault occurs for <5% duty cycle.
The duty cycle is less than 5% for the whole range of the throttle pedal.
- OK - The duty cycle is less than 5% for the whole range of the throttle pedal. Proceed to Test Step 2.
- NOT OK - The signal from the sensor is only invalid for part of the throttle pedal range
Repair: The sensor is not adjusted correctly. Adjust the throttle pedal linkage so the sensor signal is valid through the entire range.
Test Step 2. CHECK THE SENSOR
- The key start switch remains in the ON position.
- Ensure that the diagnostic code is active.
- Observe the status of the diagnostic code. Disconnect the sensor from the machine harness.
The CID 0091 FMI 04 remains active. The FMI has not changed and the "04" is still active.
- OK - The diagnostic code remains active. The sensor is correct. Proceed to Test Step 3.
- NOT OK - The diagnostic code is no longer active or the FMI has changed from "04" to "03".
Repair: Replace the sensor or repair the harness.
Test Step 3. CHECK THE WIRING HARNESS OF THE SENSOR FOR A SHORT TO GROUND.
- Disconnect the negative battery cable and turn the key start switch to the OFF position.
- Disconnect the machine harness from the sensor.
- Disconnect the machine harness connector(s) from the ECM.
- At the machine harness connector for the ECM, measure the resistance from the signal contact J2-48 (wire T914-OR) of the machine harness to all possible sources of ground. Measure the resistance to all contacts of the machine harness connectors for the ECM.
Each resistance measurement is greater than 5000 ohms.
- OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 4.
- NOT OK - One or more resistance measurements is not correct. There is a short in the machine harness.
Repair: The short is between signal contact J2-48 (wire T914-OR) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.
Test Step 4. CHECK IF THE DIAGNOSTIC CODE REMAINS.
- Inspect the contacts of the harness connectors and clean the contacts.
- Reconnect all harness connectors.
- Turn the key start switch to the ON position.
- Operate the machine.
- Check the status of the CID 0091 FMI 04.
The CID 0091 FMI 04 is active.
- YES - The CID 0091 FMI 04 is active. The diagnostic code has not been corrected. The ECM may have failed.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
- NO - The CID 0091 FMI 04 is not active. The diagnostic code does not exist at this time.
Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.