AD30 Underground Articulated Truck Power Train Electronic Control System Caterpillar

Illustration 1	g01171873
Schematic of the hoist coil for retract

This diagnostic code is associated with the hoist coil for retract. This diagnostic code is recorded when the Power Train/Chassis Electronic Control Module (ECM) reads the voltage of the coil circuit as being above normal. The circuit is shorted to the +battery circuit.

The possible causes of this failure are listed:

• The circuit for the coil is shorted to the +battery.

• The ECM has failed. This is unlikely.

Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 1280 FMI 03 is active before performing this procedure.

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

System Response:

The hoist coil for retract is always energized. The ECM will activate the hoist coil for eject in order to keep the ejector system from moving. The ejector system will not operate. After the diagnostic code has been corrected, return the hoist control lever to the HOLD position. The hoist control lever is returned to the HOLD position before the ejector system will operate properly.

Test Step 1. CHECK THE SIGNAL CIRCUIT FOR A SHORT

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

2. Disconnect the machine harness from the coil.

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

4. At machine harness connector J1, measure the resistance from the coil signal contact J1-52 (wire G705-GN) to all other J1 and J2 connector contacts.

Expected Result:

Each resistance should be greater than 5 ohms.

Results:

• YES - Each resistance is greater than 5 ohms. The machine harness is correct. Proceed to Test Step 2.

• NO - There is a short in the machine harness.

  Repair: The short is between the signal contact J1-52 (wire G705-GN) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.

  Stop.

Test Step 2. 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 battery disconnect switch and the key start switch to the ON position.

4. Operate the machine.

5. Check the status of the CID 1280 FMI 03.

Expected Result:

The CID 1280 FMI 03 is active.

Results:

• YES - The CID 1280 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. Refer to Systems operation, Troubleshooting, Testing and Adjusting, "Electronic Control Module (ECM) - Replace" for the machine that is being serviced.

  Stop.

• NO - The CID 1280 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.