IT28G Integrated Toolcarrier and 924G, 924GZ and 928G Wheel Loaders Caterpillar

Illustration 1	g00896007
Schematic of the circuit of the temperature sensor (torque converter oil)

This diagnostic code is recorded when the ECM reads the signal voltage of the temperature sensor (torque converter oil) and the voltage is too high. The possible causes of this diagnostic code are listed here:

• The sensor has failed.

• The return circuit of the sensor is open in the machine harness.

• The signal circuit in the machine harness is shorted to a source of positive voltage.

• The signal circuit in the machine harness is open or the sensor is disconnected.

• The ECM has failed. This is unlikely.

Test Step 1. CHECK THE CONTROL AND THE HARNESS.

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

2. Disconnect the machine harness connector from the temperature sensor (torque converter oil).

3. At the machine harness connector for the sensor, measure the voltage (DCV) between the signal contact 1 (wire 443-YL(Yellow)) and the return contact 2 (wire 202-BK(Black)).

Expected Result:

The voltage is between 4.5 and 8.0 DCV.

Results:

• OK - The voltage is between 4.5 and 8.0 DCV. The ECM and the harness are correct.

  Repair: Replace the sensor.

  STOP

• NOT OK - The voltage is not between 4.5 and 8.0 DCV. The ECM may have failed or the harness has failed. Proceed to Test Step 2.

Test Step 2. CHECK THE RETURN CIRCUIT OF THE HARNESS.

1. The sensor remains disconnected.

2. Turn the disconnect switch (if equipped) and the key start switch to the OFF position.

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

4. Measure the resistance of the return circuit between contact 2 (wire 202-BK(Black)) of the machine harness for the sensor and contact J1-13 of the machine harness for the ECM.

Expected Result:

The resistance is less than 5.0 ohms.

Results:

• OK - The resistance is less than 5.0 ohms. The harness resistance is correct. Proceed to Test Step 3.

• NOT OK - The resistance is greater than 5.0 ohms. The ground circuit in the harness has failed. There is an open circuit between the ground contact and frame ground.

  Repair: Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK FOR A SHORTED HARNESS

1. The sensor and the ECM remain disconnected from the machine harness.

2. The disconnect switch and the key start switch remain in the OFF position.

3. At the machine harness connector for the sensor, measure the resistance between the signal contact 1 (wire 443-YL(Yellow)) and all contacts that are used in the machine harness connector for the ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - Each resistance measurement is greater than 5000 ohms. The ECM has failed.

  Repair: It is unlikely that an ECM has failed. Exit this procedure. Perform this CID 0826 FMI 03 procedure again. If the failure is not found, replace the ECM. Refer to the Troubleshooting, "Electronic Control Module (ECM) - Replace".

  STOP

• NOT OK - One or more resistance measurements is not correct. There is a short in the machine harness. The short is between the signal contact J1-29 (wire 443-YL(Yellow)) and the circuit with the low resistance measurement.

  Repair: Repair the machine harness or replace the machine harness.

  STOP