24M Motor Grader Power Train Electronic Control System MID 027 - CID 0379 - FMI 03 Caterpillar

Conditions Which Generate This Code:

Illustration 1	g01392115
"Machine Lube Pressure Sensor Connections"

This diagnostic code is associated with the autolube pressure sensor of the machine. The FMI 03 means that the "Transmission/Chassis ECM" has detected that the voltage of the sensor circuit is above 8 ±0.3 VDC .

Conditions that can cause this diagnostic code to be activated are listed:

• The sensor has failed.

• The signal circuit in the machine harness is open.

• The sensor power supply is open.

• The ECM has failed.

Note: 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, that all connections in the circuit are secure, and that all connections in the circuit are 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: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected.

Test Step 1. CHECK THE RESISTANCE OF THE SENSOR

1. Turn the key start switch to the OFF position then turn the disconnect switch to the OFF position.

2. Disconnect the machine harness connector from the sensor.

3. At the connector for the sensor, measure the resistance between contact A and contact B.

Expected Result:

The resistance measurement is less than 5.0 ohms.

Results:

• OK - The resistance measurement is less than 5.0 ohms. The resistance of the sensor is correct. Proceed to Test Step 2.

• NOT OK - The resistance measurement is greater than 5000 ohms. The sensor has failed.

  Repair: Replace the Autolube Pressure Sensor. Ensure that the new sensor corrects the problem.

  STOP

Test Step 2. CHECK THE SIGNAL CIRCUIT OF THE HARNESS

The sensor remains disconnected from the machine harness. The disconnect switch and the key start switch remain in the OFF position.

1. Disconnect the J1 and J2 machine harness connectors from the ECM.

2. At the machine harness connector J1, measure the resistance from the signal circuit at contact J1-44 (wire T998-BR(Brown)) to frame ground. Measure the resistance from the signal circuit at contact J1-44 (wire T998-BR(Brown)) to all the other contacts that are used in the J1 and J2 connectors for the ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - Each resistance measurement is greater than 5000 ohms. The circuit is not shorted in the machine harness. Proceed to Test Step 3.

• NOT OK - One or more of the resistance measurements are less than 5000 ohms. The signal circuit for the sensor is shorted to another circuit or to frame ground in the machine harness.

  Repair: The short is between signal wire T998-BR(Brown)and the circuit with the low resistance measurement.

  Refer to the complete schematic of the electrical system of the machine. Ensure that all connections in the signal circuit for the sensor are clean, that all connectors are secure and that all connectors are in good condition.

  For information on testing for short circuits and finding short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test". Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK THE STATUS OF THE DIAGNOSTIC CODE

1. Inspect the harness connectors. Clean the contacts of the harness connectors. Check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.

2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.

3. Reconnect all harness connectors. Make sure that the connectors are fully seated and that the clips for the connectors are fastened.

4. Turn the disconnect switch to the ON position then turn the key start switch to the ON position.

5. Operate the machine.

6. Check the status of the CID 0379 FMI 03 diagnostic code.

Expected Result:

The CID 0379 FMI 03 diagnostic code is not active.

Results:

• OK - The CID 0379 FMI 03 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation.

  STOP

• NOT OK - The CID 0379 FMI 03 diagnostic code is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: Check the sensor circuit again. The AVSpare "Electronic Technician (ET)" service tool is used to perform a wiggle test on the machine wiring harness. A wiggle test can be used to detect intermittent short circuits. A wiggle test can also be used to detect open connections in the machine wiring harness.

  If the cause cannot be found, the ECM may have failed.

  Prior to replacing an ECM, always contact your dealership "“Technical Communicator”" for possible consultation with AVSpare. This consultation may greatly reduce repair time. If the cause of the diagnostic code is not found, replace the "Machine ECM". Refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP