Cat® Command For Hauling Caterpillar

MID 039 - Machine Control Module

CID 3458 - Autonomous Steering Enable Valve Displacement Sensor

FMI 04 - Voltage Below Normal

Illustration 1	g03814403

This diagnostic code is recorded when the Input/Output Module (I/O Module) reads the voltage from the "SEL Valve Spool Pos" as being below normal or shorted to ground.

Test Step 1. CHECK THE SENSOR.

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

2. Ensure that the diagnostic code is active.

3. Observe the status of the diagnostic code. Disconnect the machine harness from the sensor.

Expected Result:

The diagnostic code will remain active if the sensor is not the cause of the diagnostic code. The sensor is the cause of the diagnostic code if the diagnostic code is NO longer active.

Results:

• OK - The diagnostic code remains active. The sensor has NOT failed. The machine harness may have failed or the I/O Module may have failed. Proceed to Test Step 2.

• NOT OK - The diagnostic code is NO longer active. The machine harness and the I/O Module are operating properly.

  Repair: The sensor has failed. Replace the sensor.

  STOP

Test Step 2. CHECK THE CIRCUIT FOR A SHORT TO GROUND.

1. The sensor remains disconnected from the machine harness.

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

3. Disconnect the machine harness connector J1 from the I/O Module.

4. At the machine harness connector J1, measure the resistance from contact 36 (wire U736-YL(Yellow)) to all possible sources of ground.

Expected Result:

The resistance should be greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.

• NOT OK - The resistance is less than 5000 ohms. There is a short in the machine harness.

  Repair: The short is between the circuits with the low resistance measurement. Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.

1. Clean the contacts of the harness connectors.

2. Reconnect all harness connectors.

3. Observe the status of the diagnostic code.

4. Operate the machine.

5. Observe the status of the diagnostic code.

Expected Result:

The diagnostic code is NO longer active.

Results:

• YES - The diagnostic code is NO longer active. 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 that was disconnected and then reconnected. Resume normal machine operation

  STOP

• NO - The diagnostic code has not been corrected. The ECM has failed.

  Repair: It is unlikely that the I/O Module has failed. Exit this procedure and perform this diagnostic code procedure again. Replace the I/O Module if the cause of the diagnostic code is not found. Prior to replacing an I/O Module, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. Refer to Testing and Adjusting, KENR8394, "Electronic Control Module (ECM) - Replace".

  STOP