988G Wheel Loader Electrohydraulic System MID 082 - CID 1964 - FMI 08 Caterpillar

Conditions Which Generate This Code:

Illustration 1	g01959385
Schematic for the lift cylinder position sensor

Note: This sensor is found on machines that are equipped with the steel mill attachment.

This diagnostic code is associated with the lift cylinder position sensor. The CID 1964 FMI 08 means that the ECM has determined that the signal frequency or the signal pulse width is not within the expected range.

The output frequency of the position sensor is approximately 115 ± 15 hertz. The duty cycle of the signal changes as the position sensor moves. The duty cycle varies from 2 to 80%.

The possible causes of this diagnostic code are listed below:

• Having an Intermittent connection or a poor connection in the sensor supply or the sensor return signal.

• The sensor has failed.

• Mechanical devices are loose.

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

Test Step 1. CHECK THE OPERATION OF THE POSITION SENSOR

1. Check the voltage of the battery that is inside of the test box. Then release the button that is on the side of the test box.

2. Disconnect the machine harness connector from the sensor for the cylinder. Plug the test box of the harness connector (4) into the connector for the cylinder.

   Note: If the Sensor Test Box is not available, leave the sensor connected to the machine harness. Use a digital multimeter and 7X-1710 Multimeter Probes to measure the signal between the signal pin and the ground pin at the sensor.

3. Measure the PWM frequency of the sensor and the duty cycle of the sensor while operating the cylinder through the full range of motion.

Results:

• OK - The duty cycle and the frequency of the sensor signal are correct. The position sensor is not the cause of the diagnostic code. Proceed to Test Step 2.

• NOT OK - Either the duty cycle or the frequency of the sensor signal are not within the acceptable limits. The position sensor is faulty.

  Repair: Replace the position sensor.

  STOP

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

1. Disconnect the connector to the position sensor from the harness.

2. The disconnect switch remains in the OFF position.

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

4. At the machine harness ECM connectors, measure the resistance from the signal contact J2-35 (wire C530-BU(Blue)) to all ECM ground and frame ground contacts on connectors J1 and J2. The ground contacts on connector J1 are J1-2, J1-5, J1-7, J1-15 and J1-16. The ground contact on connector J2 is J2-3. Also, check the resistance to frame ground.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - The resistance measurement for each circuit is greater than 5000 ohms. Proceed to Test Step 3.

• NOT OK - One or more of the resistance measurement is less than 5000 ohms. The harness has failed.

  Repair: There is a short in the machine harness between the sensor signal wire C530-BU(Blue) and the ground circuit with the low measurement. Repair the harness or replace the harness.

  STOP

Test Step 3. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO THE +BATTERY CIRCUIT

1. The disconnect switch remains in the OFF position. The sensor connector remains disconnected from the harness.

2. At the machine harness connector for the implement ECM, measure the resistance from contact J2-35 (wire C530-BU(Blue)) to all J1 contacts that are connected to the +battery. The J1 contacts are J1-1, J1-6, J1-40. Check through J2-9 and J2-12

Expected Result:

All resistance measurement is greater than 5000 ohms.

Results:

• OK - All resistance checks are greater than 5000 ohms. Proceed to Test Step 4.

• NOT OK - One or more of the resistance checks measure less than 5000 ohms. The machine harness has failed.

  Repair: There is a short between the +battery circuit and the position sensor signal wire (C530-BU(Blue)). Repair the machine harness or replace the machine harness.

  STOP

Test Step 4. CHECK THE SENSOR CIRCUIT FOR AN OPEN CIRCUIT

1. The disconnect switch remains in the OFF position.

2. At the machine harness connector for the position sensor, connect a jumper wire between connector contact 1 (wire P994-BU(Blue)) and connector contact 3 (C530-BU(Blue)).

3. At the harness connectors for the ECM, measure the resistance between connector contact J2-9 (wire P994-BU(Blue)) and connector contact J2-35 (wire C530-BU(Blue)). Record the resistance measurement.

4. At the machine harness connector for the position sensor, connect the jumper wire between connector contact 2 (wire 299-BK(Black)) and connector contact 3 (C530-BU(Blue)).

5. At the harness connectors for the ECM, measure the resistance between connector contact J1-15 (wire 299-BK(Black)) and connector contact J2-35 (wire C530-BU(Blue)). Record the resistance measurement.

Expected Result:

All of the resistance measurements are 5 ohms or less.

Results:

• OK - All of the resistance measurements are 5 ohms or less. The wiring circuit for the sensor is not open. Proceed to Test Step 5.

• NOT OK - One or more of the resistance measurements is greater than 5 ohms. There is an open in the circuit for the sensor.

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

  STOP

Test Step 5. CHECK THE STATUS OF THE DIAGNOSTIC CODE

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

2. Turn the disconnect switch to the OFF position.

3. Perform the following:

   • Visually Inspect the harness connectors.

   • Clean the contacts of the harness connectors.

   • Visually inspect the insulation of the wires for damage that is caused by excessive heat, battery acid, or chafing.

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

5. Reconnect all harness connectors. Verify the following:

   • Connectors are fully seated.

   • Clips for each connector are completely fastened.

6. Turn the disconnect switch to the ON position.

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

8. Operate the machine.

9. Check the status of the CID 1964 FMI 08.

Expected Result:

The CID 1964 FMI 08 is active.

Results:

• YES - The CID 1964 FMI 08 is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See the Testing and Adjusting, "Electronic Control Module (ECM) - Replace" Story in this manual for additional information.

  STOP

• NO - The CID 1964 FMI 08 is not active. The diagnostic code does not exist at this time.

  Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Check the circuit again. Perform the Wiggle Test on the machine wiring harness with the AVSpare Electronic Technician (Cat ET) service tool.

  • Momentary shorts

  • Intermittent shorts

  • Opens
  If the cause of the active diagnostic code is not found, the sensor may have failed. For removal of the position sensor from the cylinder, refer to Disassembly and Assembly, REHS2808, "Process for Removal and Installation of the Position Sensor in the Lift Cylinder". After the replacement of the sensor, the new sensor should be calibrated before the machine can be operated. Refer to the Testing and Adjusting, "Position Sensor for the Lift Cylinder (Electronic Technician) - Calibrate" Story in this manual for the correct calibration procedure.

  STOP