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

Illustration 1	g00895444
Schematic of the parking brake switch

This diagnostic code is associated with the parking brake switch. The switch is connected to two inputs of the Transmission ECM. One contact is open and the other contact is grounded during proper operation.

An FMI 03 means that the ECM has determined that both input circuits are open at the same time.

Possible causes for this diagnostic code are:

• The switch circuit is shorted to a voltage source.

• There is an open circuit in the switch harness.

• The switch has failed.

• The ECM might have failed but that is unlikely.

Note: The following test procedure may create other diagnostic codes. Ignore these diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0070 FMI 03 is active before performing this procedure.

Test Step 1. CHECK THE SWITCH CIRCUITS FOR A SHORT TO ANOTHER VOLTAGE SUPPLY.

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

2. Disconnect both theJ1 and J2 machine harness connectors from the Transmission ECM.

3. Disconnect the machine harness from the parking brake switch.

4. At the harness connector for the ECM measure the resistance between contact J2-52(wire E417-OR) and all of the other contacts used in both connectors for the ECM. Next, measure the resistance between contact J2-53(wire F765-BR) and all of the other contacts used in both connectors for the ECM.

Expected Result:

Each measurement is greater than 5000 ohms.

Results:

• OK - Each measurement is greater than 5000 ohms. The harness is correct. Proceed to Test Step 2.

• NO - One or more of the measurements were not correct. There is a short in the machine harness.

  Repair: The short is between wire F765-BR and the circuit with the lowest resistance measurement or the short is between wire E417-OR and the circuit with the lowest resistance measurement. Repair, or replace, the machine harness.

  STOP

Test Step 2. CHECK THE SWITCH CIRCUITS IN THE HARNESS.

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

2. At the harness connector for the switch, connect a jumper wire between contact N/O (wire F765-BR) and contact N/C (wire E417-OR).

3. At the J2 harness connector for the ECM, measure the resistance from contact J2-52 (wire E417-OR) to contact J2-53 (wire F765-BR).

Expected Result:

The resistance is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. Proceed to Test Step 3.

• NOT OK - The resistance is not correct. The circuit is open.

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

  STOP

Test Step 3. CHECK THE NORMAL 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 N/C (wire E417-OR) of the connector for the switch.

4. Connect the other lead from a multimeter to contact N/O (wire F765-BR) of the connector for the switch.

5. Measure the resistance between contact N/C (wire E417-OR) and contact N/O (wire F765-BR). Note the resistance.

6. Disconnect the lead from contact N/O (wire F765-BR) and connect the lead to the ground contact (wire 202-BK) for the switch.

7. Measure the resistance between contact N/C (wire E417-OR) and the ground contact (wire 202-BK) for the switch.

Expected Result:

The resistance from contact N/C (wire E417-OR) to contact N/O (wire F765-BR) is more than 5000 ohms, and the resistance from contact N/C (wire E417-OR) to the ground contact (wire 202-BK) on the switch is less than 5 ohms.

Results:

• YES - The resistance from contact N/C (wire E417-OR) to contact N/O (wire F765-BR) is more than 5000 ohms, and the resistance from contact N/C (wire E417-OR) to the ground contact (wire 202-BK) on the switch is less than 5 ohms. The switch is operating correctly. Proceed to Test Step 4.

• NO - The resistance measurements are not correct. The switch has failed.

  Repair: Replace the switch.

  STOP

Test Step 4. CHECK THE ENGAGED OPERATION OF THE SWITCH

1. The machine harness remains disconnected from the switch.

2. Press and hold the switch.

3. Connect one lead from a multimeter to contact N/C (wire E417-OR) of the harness connector for the switch.

4. Connect the other lead from a multimeter to contact N/O (wire F765-BR) of the harness connector for the switch.

5. Measure the resistance between contact N/C (wire E417-OR) and contact N/O (wire F765-BR). Note the resistance.

6. Disconnect the lead from contact N/C (wire E417-OR) and connect the lead to the ground contact (wire 202-BK) for the switch.

7. Measure the resistance between contact N/O (wire F765 -BR) and the ground contact (wire 202-BK) for the switch. Note the resistance.

Expected Result:

The resistance from contact N/C (wire E417-OR) to contact N/O (wire F765-BR) is more than 5000 ohms, and the resistance from contact N/O (wire F765-BR) and the ground contact (wire 202-BK) for the switch is less than 5 ohms.

Results:

• YES - The resistance from contact N/C (wire E417-OR) to contact N/O (wire F765-BR) is more than 5000 ohms, and the resistance from contact N/O (wire F765-BR) and the ground contact (wire 202-BK) for the switch is less than 5 ohms. The switch is operating correctly. Proceed to Test Step 5.

• NO - The resistance measurements are not correct. The switch has failed.

  Repair: Replace the switch.

  STOP

Test Step 5. 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 0070 FMI 03.

Expected Result:

The CID 0070 FMI 03 is not active.

Results:

• YES - The CID 0070 FMI 03 is not active. The diagnostic code does not exist at this time.

  Repair: The diagnostic code was probably caused by a poor electrical connection that was resolved when a harness connector was disconnected and reconnected. Resume normal machine operation.

  STOP

• NO - The CID 0070 FMI 03 is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: Is unlikely that the Transmission ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, contact your Dealership Technical Communicator for possible consultation with Caterpillar.If the Transmission ECM needs to be replaced, see Troubleshooting, "Electronic Control Module (ECM) - Replace".

  STOP