992G Wheel Loader and 854G Wheel Dozer Power Train Caterpillar

The circuit for the Quickshift Switch has two inputs for the ECM. One contact is open and the other contact is grounded during proper operation. A failure is detected when both inputs are in the open state.

The possible causes of the problem are listed below:

• The machine harness has failed.

• The switch has failed.

• The ECM has failed. This is unlikely.

Illustration 1	g01069923
Schematic of the Quickshift Enable Switch

Test Step 1. CHECK THE GROUND CIRCUIT OF THE SWITCH IN THE HARNESS.

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

2. Disconnect the machine harness connector(s) from the ECM.

3. Measure the resistance between contact J1-16 (wire 202-BK) of the machine harness for the ECM and the contact 2 (wire 202-BK).

4. Also measure the resistance between contact J1-16 (wire 202-BK) of the machine harness for the ECM and the contact 5 (wire 202-BK).

Expected Result:

Both resistances are less than 5 ohms.

Results:

• OK - Both resistances are less than 5 ohms. The circuit is correct. Proceed to Test Step 2.

• NOT OK - Either resistance is greater than 5000 ohms. The circuit is open. The machine harness has failed.

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

  Stop.

Test Step 2. CHECK THE SWITCH CIRCUITS FOR A SHORT TO THE +BATTERY CIRCUIT.

1. The machine harness connector(s) remains disconnected from the ECM.

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

3. Disconnect contact 3 (wire G759-WH) and contact 1 (wire G758-PU) from the connector of the switch.

4. At the machine harness connector for the ECM, measure the resistance from contact J1-29 (wire G758-PU) and contact J1-31 (wire G759-WH) of the machine harness to all the contacts that are used in the machine harness connectors for the ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

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

• NO - One or more of the measurements were less than 5 ohms. There is a short in the machine harness.

  Repair: The short is between wire G758-PU and the circuit with the lowest resistance measurement or the short is between wire G759-WH and the circuit with the lowest resistance measurement. Repair the machine harness or replace the machine harness.

  Stop.

Test Step 3. CHECK THE SWITCH CIRCUITS IN THE HARNESS.

1. The machine harness remains disconnected from the ECM and the switch.

2. At the harness connector for the switch, connect a jumper wire between contact 3 (wire G759-WH) and contact 1 (wire G758-PU).

3. At the harness connector for the ECM, measure the resistance from contact J1-31 (wire G759-WH) to contact J1-29 (wire G758-PU).

Expected Result:

The resistance is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. Proceed to Test Step 4.

• NOT OK - The resistance is greater than 5000 ohms. The circuit is open.

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

  Stop.

Test Step 4. CHECK THE OPERATION OF THE SWITCH.

1. Remove the jumper that was installed in the previous Test Step.

2. The machine harness remains disconnected from the switch.

3. Connect one lead from a multimeter to contact 2 (wire 202-BK) of the harness connector for the switch.

4. Connect the other lead from a multimeter to contact 3 (wire G759-WH) of the harness connector for the switch.

5. Measure the resistance between contact 2 (wire 202-BK) and contact 3 (wire G759-WH). Note the resistance.

6. Disconnect the lead from contact 3 (wire G759-WH) and connect the lead to contact 1 (wire G758-PU).

7. Measure the resistance between contact 2 (wire 202-BK) and contact 1 (wire G758-PU).

Expected Result:

The resistance from contact 2 (wire 202-BK) to contact 1 (wire G758-PU) is less than 5 ohms. The resistance from contact 2 (wire 202-BK) to contact 3 (wire G759-WH) is greater than 5000 ohms.

Results:

• YES - The resistance from contact 2 to contact 1 is less than 5 ohms. The resistance from contact 2 to contact 3 is greater than 5000 ohms. The switch is operating correctly. Proceed to Test Step 5.

• NO - The resistance measurements do not differ for both contacts, or the measurements have not changed from the previous Test Step. The switch has failed.

  Repair: Replace the switch.

  Stop.

Test Step 5. CHECK THE OPERATION OF THE SWITCH

1. The machine harness remains disconnected from the switch.

2. Press in the top of the switch.

3. Connect one lead from a multimeter to contact 2 (wire 202-BK) of the harness connector for the switch.

4. Connect the other lead from a multimeter to contact 3 (wire G759-WH) of the harness connector for the switch.

5. Measure the resistance between contact 2 (wire 202-BK) and contact 3 (wire G759-WH). Note the resistance.

6. Measure the resistance between contact 2 (wire 202-BK) and contact 1 (wire G758-PU).

Expected Result:

The resistance from contact 2 (wire 202-BK) to contact 3 (wire G759-WH) is less than 5 ohms. The resistance from contact 2 (wire 202-BK) and contact 1 (wire G758-PU) is greater than 5000 ohms. These measurements are opposite of the measurements from the previous Test Step.

Results:

• YES - The resistance from contact 2 to contact 3 is less than 5 ohms. The resistance from contact 5 to contact 6 is less than 5 ohms. The resistance from contact 2 and contact 1 is greater than 5000 ohms. These measurements are opposite of the measurements from the previous Test Step. The switch is operating correctly. Proceed to Test Step 6.

• NO - The resistance measurements do not differ for both contacts, or the measurements have not changed from the previous Test Step. The switch has failed.

  Repair: Replace the switch.

  Stop.

Test Step 6. CHECK IF THE DIAGNOSTIC CODE REMAINS.

1. Inspect the contacts of the harness connectors and clean the harness connectors.

2. Reconnect all the harness connectors.

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

4. Operate the machine.

5. Check the status of the CID 0628 FMI 03.

Expected Result:

The CID 0628 FMI 03 is active.

Results:

• YES - The CID 0628 FMI 03 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 Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  Stop.

• NO - The CID 0628 FMI 03 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. Resume normal machine operation.

  Stop.