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| Illustration 1 | g01283430 |
Schematic of the Parking Brake Solenoid Circuit | |
This diagnostic code is recorded when the ECM detects a short to ground in the electrical path from the ECM to the solenoid.
The possible causes are listed:
- The signal circuit from the ECM to the solenoid is shorted to ground.
- The solenoid has failed.
- 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 the created diagnostic codes. Clear these diagnostic codes when the original diagnostic code is corrected.
System Response:
CID 681 FMI 05 will generate a level 2 warning. The machine will be brought to a stop and the park brake will engage. The park brake will not release until the diagnostic code has been corrected and the hystat lever has been brought back to the neutral position.
Note: Ensure that CID 0681 FMI 06 for the solenoid is active.
Note: The following procedure can create numerous related diagnostic codes. When all harnesses are reconnected, the related diagnostic codes will be shown as being not active. Clear all related diagnostic codes after this procedure is completed.
Test Step 1. CHECK THE SOLENOID
- Turn the key start switch to the ON position. Do not start the engine.
- Observe the status of the diagnostic code.
- Disconnect the solenoid with the active diagnostic code from the machine harness.
Expected Result:
The active CID 0681 FMI 06 diagnsotic code changes to a CID 0681 FMI 05 diagnostic code when the solenoid is disconnected.
Results:
- YES - The active CID 0681 FMI 06 diagnostic code changes to a CID 0681 FMI 05 diagnostic code when the solenoid is disconnected. The solenoid circuit in the machine harness is correct.
Repair: The solenoid has failed. Inspect the harness to the solenoid for any failures. Repeat this test "CHECK THE SOLENOID" in order to verify the solenoid failure. Replace the solenoid.
STOP
- NO - The CID 0681 FMI 06 diagnostic code remains active. Disconnecting the solenoid did not change the status of the active diagnostic code. The solenoid is not causing the problem. Proceed to Test Step 2.
Test Step 2. CHECK THE ENERGIZE CIRCUIT OF THE SOLENOID FOR A SHORT TO GROUND
The solenoid remains disconnected from the machine harness.
- Disconnect the negative battery cable and turn the key start switch to the OFF position.
- Disconnect the machine harness ECM connectors J1 and J2 from the ECM.
- At the machine harness ECM connectors, measure the resistance from the signal contact J2-2 (wire A958-WH) to frame ground. Measure the resistance from the signal contact J2-2 (wire A958-WH) to all of the other contacts that are used in J1 and J2 ECM connectors.
- While observing the multimeter resistance measurements, wiggle the machine harness connectors for the ECM and the solenoid. Gently pull on the wires and move the wires around.
Expected Result:
Each resistance measurement is greater than 5000 ohms at all times during the manipulation of the harness and connectors.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
- NOT OK - One or more of the resistance measurements is less than 5000 ohms. The resistance measurement is indicating that a short is present in the machine harness. The short is between wire A958-WH and either frame ground or the circuit with the low resistance measurement.
Repair: 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 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 sensor circuit.
- Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are completely fastened.
- Reconnect the negative battery cable and turn the key start switch to the ON position.
- Operate the machine.
- Check the status of the CID 0681 FMI 06 diagnostic code.
Expected Result:
The CID 0681 FMI 06 diagnostic code is still active.
Results:
- YES - The CID 0681 FMI 06diagnostic code is still active. The diagnostic code 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.Verify that all possible causes of the diagnostic code have been investigated. Exit this procedure and perform this procedure again. If the cause of the problem is not found, the ECM may have failed.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 06 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.
STOP