Cat® Command For Hauling Caterpillar

MID 039 - Machine Control Module

CID 0730 - Auto/Manual Cab Switch

FMI 03 - Voltage Above Normal

Illustration 1	g03204492

The Autonomous/Manual Mode Cab Switch has two inputs to the Input/Output Module (I/O Module). The two inputs are normally open and normally closed. During normal operation, one of the inputs is open. The other input is grounded. When a circuit is measured with a voltmeter, an open circuit will measure approximately 13 DCV to ground and a closed circuit will measure approximately 0 DCV to ground.

An FMI 03 diagnostic code is recorded when the status of both the inputs are open.

The possible causes of this diagnostic code are listed below:

• The return circuit (wire A274-BK(Black)) is open.

• Switch contact "1" signal circuit (wire F901-GY(Grey)) is permanently open.

• Switch contact "3" signal circuit (wire F900-WH(White)) is permanently open.

• The switch has failed.

• The Input/Output Module (I/O Module) has failed. This failure is unlikely.

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: Ensure that the diagnostic code CID 0729 - FMI 03 is active before performing this procedure.

Test Step 1. CHECK THE GROUND CIRCUIT FOR AN OPEN

1. Turn the disconnect switch and the keyswitch to the OFF position.

2. Disconnect the machine harness connectors from the I/O Module.

3. Disconnect the switch from the machine harness.

4. Measure the resistance between chassis ground and contact 2 (wire A274-BK(Black)) at the machine harness connector for the switch.

Expected Result:

The resistance should be less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. Proceed to Test Step 2.

• NOT OK - The resistance is greater than 5 ohms.

  Repair: The return circuit (wire A274-BK(Black)) is open in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 2. CHECK THE SWITCH

1. Check for continuity between contact 1 and contact 2 of the switch.

2. Press the switch and then release the switch while checking for continuity.

3. Check for continuity between contact 2 and contact 3 of the switch.

4. Press the switch and then release the switch while checking for continuity.

Expected Result:

The continuity check agrees with the preceding Table 1.

Results:

• OK - The continuity check agrees with the preceding Table. Proceed to Test Step 3.

• NOT OK - The continuity check does not agree with the preceding Table. The switch has failed.

  Repair: Replace switch. Verify that the new switch corrects the diagnostic code.

  STOP

Test Step 3. CHECK THE SIGNAL CIRCUITS FOR AN OPEN

1. Reconnect the switch to the machine harness.

2. The machine harness connectors remain disconnected from the I/O Module.

3. At the machine harness connector for the I/O Module, check for continuity between contact 41 (wire F900-WH(White)) and frame ground.

4. Press the switch and then release the switch while checking for continuity.

5. At the machine harness connector for the I/O Module, check for continuity between contact 40 (wire F901-GY(Grey)) and frame ground.

6. Press the switch and then release the switch while checking for continuity.

Expected Result:

The continuity check agrees with the preceding Table 1.

Results:

• OK - The continuity check agrees with the preceding Table.

  Repair: If the cause of the problem is not found, contact the Technical Communicator for the Cat Dealer, for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the I/O Module requires replacement, refer to Testing and Adjusting, KENR8394, "Electronic Control Module (ECM) - Replace"..

  STOP

• NOT OK - The continuity check does not agree with the preceding Table.

  Repair: There is an open in the signal circuits of the machine harness. Repair the machine harness or replace the machine harness.

  STOP