793F Series AC Off-Highway Truck/Tractor Braking System Caterpillar

Illustration 1	g02730489
Schematic of the "ARC Control" solenoid

This diagnostic code is associated with the "ARC Control" solenoid. The FMI 05 diagnostic code is recorded when the Brake ECM has determined that the current of the solenoid is below normal.

The possible causes of this diagnostic code are listed below:

• There is an open connection in the energize circuit of the solenoid.

• The solenoid has failed.

• The ECM has failed. This situation 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 1608 FMI 05 is active before performing this procedure.

Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.

System Response:

The rear retarder control solenoid is always de-energized. The Brake ECM will not be able to energize the rear retarder control solenoid. The "Automatic Retarder Control (ARC)" will continue to operate using the "Front Retarder Control" solenoid. The ARC system will operate at a reduced level of performance.

Test Step 1. CHECK THE SOLENOID.

1. Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.

2. Disconnect the solenoid with the active diagnostic code from the machine harness.

3. At the machine harness connector for the solenoid, place a jumper wire from contact 1 (wire K988-WH(White)) to contact 2 (wire J815-BK(Black)).

4. Observe the status of the CID 1608 FMI 05 diagnostic code.

Expected Result:

The CID 1608 FMI 05 diagnostic code remains active. The diagnostic code is not active as the jumper wire is removed and installed.

Results:

• YES - The diagnostic code remains active. The jumper wire does not affect the diagnostic code. Proceed to Test Step 2.

• NO - The diagnostic is no longer active. The solenoid has failed.

  Repair: The solenoid has failed. Repeat this Test Step "CHECK THE SOLENOID" to verify the solenoid failure. Replace the solenoid. Verify that the new solenoid corrects the problem.

  STOP

Test Step 2. CHECK THE HARNESS FOR AN OPEN.

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

2. Disconnect the machine harness J1 connector from the Brake ECM.

3. The jumper wire that was installed in the previous Test Step remains in place.

4. At the machine harness J1 connector, measure the resistance from signal contact J1-54 (wire J815-BK(Black)) to contact J1-67 (wire K988-WH(White)).

Expected Result:

The resistance is less than 5.0 ohms.

Results:

• YES - The resistance is less than 5.0 ohms. The machine harness is correct. Proceed to Test Step 3.

• NO - The resistance is greater than 5000 ohms. The resistance measurement is not correct. There is an open circuit in the machine harness.

  Repair: The open is in wire J815-BK(Black) or in wire K988-WH(White) of the machine harness. Repair or replace the machine harness.

  STOP

Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.

1. Inspect the contacts of the harness connectors and clean the harness connectors.

2. Reconnect all harness connectors.

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

4. Operate the machine.

5. Check the status of the CID 1608 FMI 05 diagnostic code.

Expected Result:

The CID 1608 FMI 05 diagnostic code is active.

Results:

• YES - The CID 1608 FMI 05 diagnostic code is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: A failure of the Brake ECM is unlikely. Exit this procedure and perform this procedure again. Prior to replacing an ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NO - The CID 1608 FMI 05 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 at one of the harness connectors. Resume normal machine operation.

  STOP