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| Illustration 1 | g02719178 |
Schematic of the secondary steering relay | |
This diagnostic code is associated with the secondary steering relay. The FMI 06 diagnostic code is recorded when the ECM reads the current of the relay circuit as above normal (short to ground).
Possible causes of this diagnostic code are listed below:
- The energizer circuit of the relay is shorted to ground.
- The relay has failed.
- The Chassis ECM has failed. A failure of the ECM 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 0420 FMI 06 is active before performing this procedure.
Note: Use a digital multimeter for the measurements in this procedure.
System Response:
The system for the secondary steering will be OFF at all times.
Test Step 1. CHECK THE RELAY.
- 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.
- Disconnect the machine harness from the relay.
- 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 changes to "NOT active" when the relay is disconnected.
Results:
- YES - The circuit is correct. The relay has failed.
Repair: Repeat this test step "CHECK THE RELAY" to verify that the relay has failed. Replace the relay.
STOP
- NO - The diagnostic code remains active. Proceed to Test Step 2.
Test Step 2. CHECK THE SIGNAL CIRCUIT OF THE RELAY FOR A SHORT.
- Turn the disconnect switch and the key start switch to the OFF position.
- Disconnect the machine harness from the relay.
- Disconnect the machine harness connectors J1 and J2 from the Chassis ECM.
- At the J1 and J2 machine harness connectors for the ECM, measure the resistance from the signal contact of the relay J2-2 (wire 727-GN) to all possible sources of ground.
Expected Result:
Each resistance should be greater than 5000 ohms.
Results:
- YES - The machine harness is correct. Proceed to Test Step 3.
- NO - There is a short in the machine harness.
Repair: The short is between the signal contact of the relay and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
- Inspect the harness connectors. Clean the contacts of the harness connectors. 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. Observe that the clips for each connector are fastened securely.
- Turn the key start switch to the ON position.
- Clear all of the inactive diagnostic codes.
- Operate the machine.
- Stop the machine. Then place the parking brake switch in the ON position.
- Determine if the CID 0420 FMI 06 is active.
Expected Result:
The diagnostic code for the relay is NO longer present.
Results:
- YES - The diagnostic code is NOT present. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection and/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 Chassis 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 shorts and opens in the machine wiring harness that are momentary or intermittent. A failure of the ECM is unlikely. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. Prior to replacing an ECM, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP