TH31-C9I, TH31-C9P, TH31-C9T, TH35-C11I, TH35-C13I, TH35-C13T, TH35-C15I and TH35-C15T Petroleum Power Train Packages and TH31-E61 and TH35-E81 Petroleum Transmissions Power Train Electronic Control System Caterpillar

Illustration 1	g01298952
Schematic of the position sensor

The diagnostic trouble code is associated with the position sensor. The diagnostic trouble code is recorded when the ECU has determined that the voltage of the circuit for the sensor is below normal.

The possible causes for this diagnostic trouble code are listed:

• The sensor supply circuit to the sensor is shorted to ground.

• A sensor has failed.

• The ECU has failed. This is unlikely.

Note: The following test procedure may create other diagnostic trouble codes. Ignore these created diagnostic trouble codes and clear the diagnostic trouble codes when the original diagnostic trouble code has been corrected. Ensure that the diagnostic trouble code of CID 1824 FMI 04 is active before performing this procedure.

Note: Use the digital multimeter for the measurements in this procedure.

Test Step 1. CHECK THE SENSOR

1. Turn the disconnect switch and the key start switch to the ON position.

2. Ensure that the diagnostic trouble code is active.

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

Expected Result:

The CID 1824 FMI 04 remains active. The FMI has not changed and the "04" is still active.

Results:

• OK - The diagnostic trouble code remains active. The sensor is correct. Proceed to Test Step 2.

• NOT OK - The diagnostic trouble code is no longer active. The sensor has failed.

  Repair: Replace the sensor.

  STOP

Test Step 2. CHECK THE WIRING HARNESS OF THE SENSOR FOR A SHORT TO GROUND

1. Turn the key start switch and the disconnect switch to the OFF position.

2. Disconnect the machine harness from the sensor.

3. Disconnect the machine harness connector(s) from the ECU.

4. At the machine harness connector for the ECU, measure the resistance from the signal contact J2-26 (wire X955-GN) of the machine harness to all possible sources of ground. Measure the resistance to all contacts of the machine harness connectors for the ECU.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

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

• NOT OK - One or more resistance measurements is not correct. There is a short in the machine harness. The short is between signal contact J2-26 (wire X955-GN) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.STOP

Test Step 3. CHECK IF THE DIAGNOSTIC TROUBLE CODE IS STILL ACTIVE.

1. Inspect the harness connectors. Clean the contacts of the harness connectors and 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 circuit.

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

4. Turn the disconnect switch and the key start switch to the ON position.

5. Operate the machine.

6. Determine if the CID 1824 FMI 04 is active.

Expected Result:

The CID 1824 FMI 04 is active.

Results:

• YES - The CID 1824 FMI 04 is active. The problem has not been corrected.

  Repair: Check the circuit again. If the Caterpillar Electronic Technician (ET) is available, use the Cat ET service tool in order to perform a "Wiggle Test" on the machine wiring harness. The "Wiggle Test" can detect shorts and opens in the machine wiring harness that are momentary or intermittent. It is unlikely that the ECU has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic trouble code is not found, replace the ECU. Prior to replacing an ECU, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Testing and Adjusting, "Electronic Control Unit - Replace".

  STOP

• NO - The CID 1824 FMI 04 is not active. The problem does not exist at this time.

  Repair: The initial diagnostic trouble code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.

  STOP