950K and 962K Wheel Loaders Electrohydraulic System Caterpillar

Illustration 1	g02682043
Schematic of the Main Power relay

This diagnostic code is associated with the Main Power relay. The relay is controlled by the Relay Driver Module through an "ON/OFF" output driver circuit. The FMI 05 diagnostic code is recorded when the Relay Driver Module reads the current of the relay as below normal (open circuit). This diagnostic code is activated on the Implement ECM via CAN Datalink.

The possible causes of this diagnostic code are listed below:

• The energizer circuit of the relay is open.

• The return circuit of the relay is open.

• The relay has failed.

• The Relay Driver Module has failed. This failure is unlikely.

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. Ensure that the diagnostic code of CID 3467 FMI 05 is active before performing this procedure.

Note: Use a digital multimeter for the measurements in this procedure.

Test Step 1. CHECK THE RELAY.

1. Turn the disconnect switch and the key start switch to the ON position. Do not start the engine. Ensure that the diagnostic code for the relay is active.

2. Disconnect the machine harness from the relay.

3. At the machine harness connector for the relay that is being tested, install a jumper wire. Install a jumper wire from the signal wire (C905-OR(Orange)) to ground (wire H861-PU(Purple)).

4. Observe the status of the diagnostic code. The diagnostic code is active or the diagnostic code is NOT active.

Expected Result:

The status of the diagnostic code is active. The status of the diagnostic code is NOT active as the jumper is installed and then removed.

Results:

• YES - The circuit is correct.

  Repair: The relay has failed. Replace the relay.

  STOP

• NO - The diagnostic code remains active. Proceed to Test Step 2.

Test Step 2. CHECK THE RELAY CIRCUIT FOR AN OPEN.

1. The jumper that is between the signal wire and the return wire remains installed.

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

3. Disconnect the machine harness connector J1 from the Relay Driver Module.

4. At the J1 machine harness connectors for the RDM, measure the resistance from contact J1-12 for the relay to ground (wire H861-PU(Purple)).

Expected Result:

There should be continuity (less than 5.0 ohms resistance).

Results:

• YES - The machine harness is correct. Proceed to Test Step 3.

• NO - There is an open circuit in the machine harness.

  Repair: The open circuit is in the signal wire (C905-OR(Orange)) or in ground wire (H861-PU(Purple)) of the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.

1. 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.

2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.

3. Reconnect all harness connectors. Make sure that the connectors are fully seated and locked.

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

5. Clear all of the inactive diagnostic codes.

6. Operate the machine.

7. Stop the machine and place the parking brake switch in the ON position.

8. Observe the status of the diagnostic code. The diagnostic code is active or the diagnostic code is NOT active.

Expected Result:

The diagnostic code is NO longer active.

Results:

• YES - The diagnostic code is NO longer active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors. Resume normal machine operation.

  STOP

• NO - The diagnostic code has not been corrected. A failure of the ECM is unlikely.

  Repair: Check the circuit again. Use the Cat ET service tool in order to perform a “Wiggle Test” on the machine wiring harness. The “Wiggle Test” can detect intermittent short circuits and momentary open circuits in the wiring harness of the machine.

  A failure of the ECM/RDM is unlikely. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM/RDM. Prior to replacing an ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP