R2900G Load Haul Dump Power Train Electronic Control System Caterpillar

Illustration 1	g03159457
Schematic of the parking brake oil pressure sensor circuit

This diagnostic code is associated with the parking brake oil pressure sensor. The FMI 04 means that the Electronic Control Module (ECM) has determined that the voltage of the circuit for the position sensor is below normal.

The pressure sensor is a Pulse Width Modulated (PWM) sensor that uses a frequency of approximately 500 Hz. The duty cycle operates from a range of 10% to 90%.

The possible causes of this diagnostic code are listed below:

• The signal circuit for the sensor is shorted to ground

• The sensor has failed

• The ECM may have failed, but 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 CID 2976 FMI 04 is active before performing this procedure.

Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.

Test Step 1. CHECK THE SENSOR

1. Turn the disconnect switch and the key start switch to the ON position.

2. Ensure that the diagnostic code is active.

3. Observe the status of the diagnostic code. Disconnect the sensor from the machine harness.

Expected Result:

CID 2976 FMI 04 remains active.

Results:

• YES - CID 2976 FMI 04 remains active. The sensor is correct. Proceed to Test Step 2.

• NO - CID 2976 FMI 04 is no longer active. The sensor has failed.

  Repair: Replace the sensor.

  STOP

Test Step 2. CHECK THE WIRING HARNESS OF THE SENSOR FOR A SHORT TO GROUND

1. Turn the key start switch and the disconnect switch to the OFF position.

2. Disconnect the machine harness from the sensor.

3. Disconnect the machine harness connector from the ECM.

4. At the machine harness connector for the ECM, measure the resistance from the signal contact J2-24 (wire K491-WH(White)) of the machine harness to all possible sources of ground. Measure the resistance to all contacts of the machine harness connectors for the ECM.

Expected Result:

Each resistance measurement is greater than 5 ohms.

Results:

• YES - Each resistance measurement is greater than 5 ohms. The machine harness is correct. Proceed to Test Step 3.

• NO - One or more resistance measurements are not correct. There is a short in the machine harness.

  Repair: The short is between signal contact J2-24 (wire K491-WH(White)) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS

1. Inspect the contacts of the harness connectors and clean the contacts.

2. Reconnect all harness connectors.

3. Turn the disconnect switch and the key start switch to the ON position.

4. Operate the machine.

5. Check the status of CID 2976 FMI 04.

Expected Result:

CID 2976 FMI 04 is active.

Results:

• YES - CID 2976 FMI 04 is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: The ECM is unlikely to have failed. Exit this procedure and perform this procedure again. Prior to replacing an ECM, always contact your dealer for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Systems Operation Troubleshooting Testing and Adjusting, " ".

  STOP

• NO - CID 2976 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

  • A short at one of the harness connectors that was disconnected and reconnected
  Resume normal machine operation.

  STOP