MID 039 - Machine Control Module
CID 0729 - Auto/Manual Ground Level Switch
FMI 04 - Voltage Below Normal
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| Illustration 1 | g03204492 |
The Autonomous/Manual Mode Ground Level 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 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 F905-YL(Yellow)) is always shorted to ground.
- The "normally closed" signal circuit (wire F906-OR(Orange)) is always shorted to ground.
- The switch has failed.
- The I/O Module has failed. This 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.
| Status of the Switch | |||
|---|---|---|---|
| MODE | J1-35 (N/O)
F905-YL(Yellow) Circuit |
J1-34 (N/C)
F906-OR(Orange) Circuit |
|
| Manual | Open | Closed | |
| Autonomous | Closed | Open | |
Test Step 1. CHECK THE SWITCH
- Check for continuity between contact 1 and contact 2 of the switch.
- Press the switch and then release the switch while checking for continuity.
- Check for continuity between contact 2 and contact 3 of the switch.
- 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
- Reconnect the switch to the machine harness.
- The machine harness connectors remain disconnected from the I/O Module.
- At the machine harness connector for the I/O Module, check for continuity between contact 35 (wire F905-YL(Yellow)) and frame ground.
- Press the switch and then release the switch while checking for continuity.
- At the machine harness connector for the I/O Module, check for continuity between contact 34 (wire F906-OR(Orange)) and frame ground.
- 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