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| Illustration 1 | g01283430 |
Schematic of the Parking Brake Solenoid Circuit | |
This diagnostic code is recorded when the ECM reads the voltage of the solenoid circuit as being above normal or shorted to +battery.
The possible causes of this diagnostic code are listed:
- The energize circuit of the solenoid is shorted to the +battery circuit.
- The ECM has failed. This is unlikely.
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, secure and 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 original diagnostic code is corrected.
System Response:
The action alarm will sound and the diagnostic indicator will flash. The hystat will allow normal operation in order to bring the machine to a safe stop.
Test Step 1. CHECK THE ENERGIZE CIRCUIT OF THE SOLENOID FOR A SHORT
- Disconnect the negative battery cable and turn the key start switch to the OFF position.
- Disconnect the machine harness connector from the solenoid. Disconnect the machine harness connectors J1 and J2 from the ECM.
- At the machine harness ECM connectors, measure the resistance from contact J2-2 (wire A958-WH) to all of the other contacts that are used in the J1 and J2 connectors for the ECM.
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- YES - Each resistance measurement is greater than 5000 ohms. The resistance measurement does not indicate a short in the machine harness. Proceed to Test Step 2.
- NO - Each resistance measurement is not greater than 5000 ohms. There is a short in the machine harness.
Repair: The short is between wire A958-WH and the circuit that has a low resistance measurement.For information on testing for short circuits and finding short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test". Repair the machine harness or replace machine harness.
STOP
Test Step 2. CHECK THE OPERATION OF THE ECM
The key start switch remain in the OFF position. The machine harness connectors for the solenoid and the ECM remain disconnected.
- At the machine harness connector J2 for the ECM, use a 151-6320 Removal Tool to remove the solenoid energize wire A958-WH and socket at contact J2-2 from the harness connector.
- Reconnect the machine harness J1 and J2 connectors to the ECM.
- Reconnect the negative battery cable and turn the key start switch to the ON position.
- Observe the status of the active CID 0681 FMI 03 diagnostic code.
Expected Result:
The CID 0681 FMI 03 diagnostic code is no longer active. A CID 0681 FMI 05 diagnostic code is now active.
Results:
- YES - The CID 0681 FMI 03 diagnostic code is no longer active. A CID 0681 FMI 05 diagnostic code has been activated after the solenoid energize circuit was disconnected. The ECM has responded correctly to the open circuit condition in the solenoid circuit.
Reinstall the disconnected solenoid energize wire back into the correct space in the ECM connector before proceeding to the next test step.
Proceed to Test Step 3. - NO - The CID 0681 FMI 03 diagnostic code remains active. The status of the active diagnostic code did not change when the solenoid energize wire was disconnected from the ECM.
Repair: The ECM has not responded correctly to the open condition in the solenoid circuit. The operation of the ECM is not correct.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 ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
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. Make sure that the connectors are fully seated and the clips for each connector are completely fastened.
- Turn the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 0681 FMI 03 diagnostic code is active.
Expected Result:
The CID CID 0681 FMI 03 diagnostic code is active.
Results:
- YES - The CID 0681 FMI 03 diagnostic code remains active.
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 problem remains, the ECM may have failed. This is unlikely because the ECM detected the open circuit condition in the solenoid circuit and activated the FMI 05 diagnostic code when the solenoid energize wire was disconnected.Verify that all possible causes of the diagnostic code have been investigated. Exit this procedure and perform this procedure again.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 and the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP
- NO - The CID 0681 FMI 03 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