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| Illustration 1 | g01242087 |
Differential Lock Solenoid Connections | |
This diagnostic code is associated with the differential lock solenoid. The FMI 04 means that the ECM has determined that the voltage of the circuit for the solenoid is below normal.
The possible causes of this diagnostic code are listed below:
- The signal circuit for the solenoid is shorted to ground.
- The solenoid 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 740 FMI 04 is active before performing this procedure.
Note: Use a digital multimeter for the measurements in this procedure.
Test Step 1. CHECK THE SOLENOID
- Turn the key start switch and the disconnect switch to the ON position.
- Disconnect the machine harness connector from the solenoid. Observe the diagnostic code.
Expected Result:
The CID 740 FMI 04 diagnostic code changed to a CID 740 FMI 03 diagnostic code when the solenoid was disconnected.
Results:
- YES - The CID 740 FMI 04 diagnostic code changed to a CID 740 FMI 03 diagnostic code when the solenoid was disconnected. The solenoid is causing the problem.
Repair: The solenoid is faulty. Replace the solenoid.
STOP
- NO - The status of the CID 740 FMI 04 diagnostic code did not change when the solenoid was disconnected. The solenoid is not causing the problem. Proceed to Test Step 2.
Test Step 2. CHECK THE ENERGIZE CIRCUIT FOR A SHORT TO GROUND
The machine harness connector remains disconnected from the solenoid.
- Turn the key start switch and the disconnect switch to the OFF position.
- Disconnect the machine harness connectors J1 and J2 from the ECM.
- At machine harness connector J1, measure the resistance from solenoid contact J1-67 (wire A975-BU) to frame ground.
Expected Result:
The resistance measurement is greater than 5000 ohms.
Results:
- YES - The resistance measurement is greater than 5000 ohms. The circuit is not shorted to ground. Proceed to Test Step 3.
- NO - The resistance measurement is less than 5000 ohms. There is a short to in the machine harness.
Repair: The solenoid energize circuit is shorted to a ground source. Refer to the complete machine Electrical System Schematic. Examine all connections in the solenoid circuit for a short to ground. Check the machine harness for locations where contact with the machine frame can occur. Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the harness connectors and clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
- Reconnect all harness connectors making sure that the connectors are fully seated and the clips for each connector are completely fastened.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 740 FMI 04 diagnostic code is active.
Expected Result:
The CID 740 FMI 04 diagnostic code is active.
Results:
- YES - The CID 740 FMI 04 diagnostic code is active. The problem has not been corrected.
Repair: Check the circuit again. Use the Caterpillar Electronic Technician (ET) service tool, if available, in order to perform a "Wiggle Test" on the machine wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness.If the cause of the problem is not found, replace the solenoid. If the diagnostic code is still active after solenoid replacement, the ECM may be faulty. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, the ECM may be faulty. Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the cause of the diagnostic code is not found, replace the ECM. See the Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NO - The CID 740 FMI 04 diagnostic code is not active. The problem 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.
STOP