993K Wheel Loader Electrohydraulic System Caterpillar

Illustration 1	g01592537
Schematic for the Lift Lever Sensor

This diagnostic code is associated with the Lift Lever Sensor. The FMI 03 means that the ECM has determined that the voltage of the circuit for the sensor is below normal.

The output frequency of the position sensor is approximately 500 hertz. The duty cycle of the signal changes as the position sensor moves.

This diagnostic code will become active if the duty cycle of the PWM sensor falls below 7% for 0.5 seconds.

The possible causes for this diagnostic code are listed:

• Loss of sensor power.

• The sensor has failed.

• The lift lever sensor rotated below the normal operating range.

• The signal circuit is shorted to ground.

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. Ensure that the diagnostic code of CID 0352 FMI 04 is active before performing this procedure.

Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.

System Response:

The machine response is listed:

• The lift function will not operate.

• The lift lever must be recentered before movement of the lift function is allowed. The diagnostic code must also be cleared before movement of the lift function is allowed.

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 is corrected.

Note: Ensure that the diagnostic code is active and that the diagnostic code indicator is active.

Test Step 1. CHECK THE HARNESS.

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

2. Disconnect the harness from the sensor.

3. Turn the key start switch to the ON position.

4. At the harness connector for the sensor, measure the voltage from the ECM between contact 2 (wire 299-BK(Black)) and contact 3 (wire H827-PK(Pink)).

Expected Result:

The voltage should be 5 ± 0.5 DCV.

Results:

• YES - The voltage measures 5 ± 0.5 DCV.

  Repair: The harness is correct. The sensor or the sensor harness has failed. Check the sensor harness. If no defect is found, replace the sensor.

  STOP

• NO - The voltage does not measure 5 ± 0.5 DCV. The ECM or the harness has failed. Proceed to test step 2.

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

1. The sensor remains disconnected.

2. Turn the disconnect switch to the OFF position.

3. Turn the key start switch to the OFF position.

4. Disconnect the harness from the ECM.

5. At the harness connector for the sensor, measure the resistance between contact 2 (wire 299-BK(Black)) and the frame ground.

Expected Result:

The resistance should be less than 5 Ohms.

Results:

• YES - The resistance is less than 5 Ohms. The harness is correct. Proceed to test step 3.

• NO - The resistance is greater than 5 Ohms.

  Repair: The ground circuit in the harness has failed. There is an open circuit between contact 2 (wire 299-BK(Black)) and the frame ground. Repair the harness or replace the harness.

  STOP

Test Step 3. CHECK FOR A SHORTED HARNESS.

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

2. The disconnect switch remains in the OFF position.

3. At the harness connector for the sensor, measure the resistance between contact 3 (wire H827-PK(Pink)) and contact 1 (wire 146-GY(Grey)).

Expected Result:

The resistance should be greater than 5000 Ohms.

Results:

• YES - The resistance is greater than 5000 Ohms. The harness circuit is correct. Proceed to test step 4.

• NO - The resistance is less than 5000 Ohms.

  Repair: The harness has failed. There is a short between wire (H827-PK(Pink)) and wire (146-GY(Grey)). Repair the harness or replace the harness.

  STOP

Test Step 4. CHECK FOR A OPEN HARNESS.

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

2. The disconnect switch remains in the OFF position.

3. Check the continuity between connector J2-24 (wire H827-PK(Pink)) and contact 3 (wire H827-PK(Pink)) for the sensor.

Expected Result:

There is continuity.

Results:

• YES - There is continuity.

  Repair: The signal circuit is correct. Ensure that the diagnostic code is still active. If the diagnostic code is active, it is unlikely that the ECM has failed. Exit this procedure and perform this troubleshooting procedure again. If the cause of the diagnostic code is not found, the ECM may have failed. Prior to replacing an ECM, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NO - There is no continuity.

  Repair: The signal circuit has failed. The signal circuit in the harness is open. Repair the harness or replace the harness.

  STOP