Cat® Command For Hauling Caterpillar

MID 039 - Machine Control Module

CID 0730 - Auto/Manual Cab Switch

FMI 04 - Voltage Below 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.

A FMI 04 diagnostic code is recorded when both of the inputs are grounded.

The possible causes of this diagnostic code are listed below:

• The "normally open" signal circuit (wire F900-WH(White)) is always shorted to ground.

• The "normally closed" signal circuit (wire F901-GY(Grey)) is always shorted to ground.

• The switch has failed.

• The 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.

Test Step 1. 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 2.

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

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

  STOP

Test Step 2. CHECK THE SIGNAL CIRCUITS FOR A SHORT TO GROUND

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 F905-YL(Yellow)) 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 F906-OR(Orange)) 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 a short in the machine harness. Repair the machine harness or replace the machine harness.

  STOP