Air Conditioning and Heating R134a for All Caterpillar Machines – MID 082 – CID 1883 – FMI 03

Conditions Which Generate This Code:



Illustration 1 g03327836

Schematic of the “Winch Low Speed Lock” solenoid

The following procedure is for the “Low Speed Lock” switch. This switch has three inputs to the ECM: “N/O” (wire F868-OR), “N/C” (wire F884-BU) and “return” (wire Y773-GY). During normal operation, one of the switch input is open and the other input is grounded. If both inputs are in the same state, the ECM will detect a diagnostic code. This diagnostic code is detected when both switch inputs are open or shorted to the +battery.

The possible causes of this diagnostic code are listed below:

  • Both inputs are open.

  • A short to the battery

  • A failed switch

  • The ECM may have failed. This is unlikely.

Note: Ensure that the CID 1883 FMI 03 diagnostic code is active. The following procedures may create other diagnostic codes that are detected by the ECM. Ignore these created diagnostic codes and clear the diagnostic code when this diagnostic code has been corrected.

System Response:

The machine response is listed below:

  • A level 2 warning will be generated.

  • The winch will not be able to switch between modes.

  • The function for the winch is not disabled.

Test Step 1. CHECK FOR AN OPEN CIRCUIT.

  1. Turn the disconnect switch and the key start switch to the OFF position.
  1. Disconnect the J1 machine harness connector from the ECM.
  1. At the J1 machine harness connector, measure the resistance from contact J2-45 (wire F868-OR) to contact J2-22 (wire Y773-GY) with the switch in the normally open position. The switch is pressed.
  1. At the J1 machine harness connector, measure the resistance from contact J2-44 (wire F884-BU) to contact J2-22 (wire Y773-GY) with the switch in the normally closed position. The switch is not pressed.

Expected Result:

The resistance should be less than 5 ohms for each measurement.

Results:

  • YES – The resistance is less than 5 ohms for each measurement. Proceed to test step 3.

  • NO – The resistance measurement is not less than 5 ohms for one or both measurements. The harness or the switch has failed. Proceed to test step 2.

Test Step 2. CHECK THE RESISTANCE OF THE SWITCH.

  1. Disconnect the machine harness from the switch.
  1. Place the switch in the normally open position. Measure the resistance of the switch from contact 7 (wire F868-OR) to contact 5 (wire Y773-GY) of the connector for the switch. The switch is pressed.
  1. Place the switch in the normally closed position. Measure the resistance of the switch from contact 6 (wire F884-BU) to contact 5 (wire Y773-GY) of the connector for the switch. The switch is not pressed.

Expected Result:

The resistance measurement should be less than 5 ohms for each measurement.

Results:

  • OK – The resistance measurements are less than 5 ohms. The switch is correct.

    Repair: The machine harness has failed. Repair the machine harness or replace the machine harness.

    STOP

  • NOT OK – The resistance is not less than 5 ohms for one or both measurements.

    Repair: The switch has failed. Replace the switch. Verify that the new switch corrects the problem.

    STOP

Test Step 3. CHECK FOR A SHORT.

  1. At the J1 machine harness connector, measure the resistance from contact J2-44 and contact J2-45 to all other J1 and J2 contacts.

Expected Result:

The resistance measurement should be greater than 5000 ohms for each measurement.

Results:

  • OK – The resistance measurement is greater than 5000 ohms for each measurement.

    Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Verify that the diagnostic code is still active. If the cause of the diagnostic code is not found, replace the Implement ECM. See Troubleshooting, “Electronic Control Module (ECM) – Replace”.

    STOP

  • NOT OK – The resistance measurement is not greater than 5000 ohms for one or more measurements.

    Repair: The short is in the circuit with the low resistance measurement. Repair the harness or replace the harness. Verify that the problem has been corrected.

    STOP

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