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| Illustration 1 | g02682043 |
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Connections of the Main Power Relay | |
This diagnostic code is associated with the Main Power Relay. This relay is powered by an "ON/OFF" driver circuit. The FMI 03 diagnostic code is activated when the Relay Driver Module detects an above normal voltage of the relay circuit. This diagnostic code is activated on the Implement ECM via CAN Datalink.
The following conditions could cause this diagnostic code to be activated:
- The relay has failed.
- The relay circuit is shorted to a power source.
- The Relay Driver Module has failed. This condition 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, that all connections are secure and that all connections are 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 these diagnostic codes when the original diagnostic code has been corrected.
Test Step 1. CHECK THE ENERGIZE CIRCUIT OF THE RELAY FOR A SHORT
- Turn the disconnect switch and the key start switch to the OFF position.
- Disconnect the machine harness connector from the relay. Disconnect the machine harness connector J1 from the Relay Driver Module.
- At the machine harness connectors for the Relay Driver Module, measure the resistance between contact J1-12 (wire C905-OR(Orange)) and each of the other circuits that are used in the J1 connector for the Relay Driver Module.
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. The resistance measurements do not indicate a short to another circuit in the machine harness. Proceed to Test Step 2.
- NOT OK - Each resistance measurement is not greater than 5000 ohms. There is a short in the machine harness.
Repair: The short is between wire C905-OR(Orange) and the circuit that measured 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 the machine harness.
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Test Step 2. CHECK THE OPERATION OF THE RELAY DRIVER MODULE
The disconnect switch and the key start switch remain in the OFF position. The machine harness connectors for the relay and the Relay Driver Module remain disconnected.
- At the machine harness connector J1 for the Relay Driver Module, use a 151-6320 Removal Tool to remove the relay wire C905-OR(Orange) and the socket at contact J1-12 from the harness connector.
- Reconnect the machine harness J1 connector to the Relay Driver Module.
- Turn the disconnect switch and the key start switch to the ON position.
- Observe the status of the active CID 3467 FMI 03 diagnostic code.
Expected Result:
The CID 3467 FMI 03 diagnostic code is no longer active. A CID 3467 FMI 05 diagnostic code is now active.
Results:
- OK - The CID 3467 FMI 03 diagnostic code is no longer active. A CID 3467 FMI 05 diagnostic code has become active after the relay circuit is disconnected. The Relay Driver Module has responded correctly to the open circuit condition in the relay circuit. Reconnect the relay wire in the Relay Driver Module connector before proceeding to the next step. Proceed to Test Step 3.
- NOT OK - The CID 3467 FMI 03 diagnostic code remains active. The status of the active diagnostic code was not changed even when the relay wire was disconnected from the Relay Driver Module.
Repair: The Relay Driver Module has not responded correctly to the open condition in the relay circuit. The operation of the Relay Driver Module is not correct.
Prior to replacing a Relay Driver Module, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time.
If the Relay Driver Module must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
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Test Step 3. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the harness connectors. Clean the contacts of the harness connectors. Check the wires for damage to the insulation that can be caused by excessive heat, battery acid, or chafing.
- Perform a
45 N (10 lb) pull test at the connectors that are used in the circuit. - Reconnect all harness connectors. Make sure that the connectors are fully seated and locked .
- Turn the disconnect switch and the key start switch to the ON position.
- Determine if the CID 3467 FMI 03 diagnostic code is active.
Expected Result:
The CID CID 3467 FMI 03 diagnostic code is active.
Results:
- OK - The CID 3467 FMI 03 diagnostic code remains active.
Repair: If available, perform a Wiggle Test on the machine wiring harness with the Caterpillar Electronic Technician (Cat ET) service tool. The Wiggle Test can detect the following in the machine wiring harness:
- Momentary shorts
- Intermittent shorts
- Opens
- The Relay Driver Module detected the open circuit condition in the relay circuit.
- The Relay Driver Module activated the FMI 05 diagnostic code when the wire that energizes the relay was disconnected.
Prior to replacing a Relay Driver Module, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. If the cause of the diagnostic code is not found and the Relay Driver Module must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
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- NOT OK - The CID 3467 FMI 03 code is not active. The problem does not exist at this time.
Repair: The initial diagnostic code could have been caused by a poor electrical connection or short at a harness connector that was disconnected and reconnected. Resume normal machine operation.
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