953C, 963C and 973C Track-Type Loaders Transmission Electronic Control System MID 079 - CID 0248 - FMI 02 Caterpillar

Conditions Which Generate This Code:

Illustration 1	g00981113
Schematic of the AVS data link circuit

This diagnostic code is recorded when the ECM does not receive expected information. The information from the AVS data link indicates the abnormal values in the readout. The possible causes of this diagnostic code are listed below. The causes are listed in order of probability:

• Poor electrical connection at a machine harness connector

• The circuit for the AVS data link in the machine harness is shorted to ground.

• The circuit for the AVS data link in the machine harness is shorted to the +battery.

• The circuit for the AVS data link in the machine harness is open.

Test Step 1. CHECK FOR OTHER CODES.

1. Check for other diagnostic codes that are related to the AVS data link.

Expected Result:

There are other diagnostic codes that are showing.

Results:

• YES - Exit this procedure and perform the other procedures for the diagnostic codes that are shown.

  STOP

• NO - There are not any other diagnostic codes that are shown. Proceed to Test Step 2.

Test Step 2. INSPECT THE HARNESS CONNECTORS.

1. Turn the disconnect switch to the OFF position.

2. Inspect the connections for the machine harness that are related to the AVS data link.

3. Make sure that connectors are clean and tight.

Expected Result:

The machine harness is correct.

Results:

• OK - The machine harness is correct. Proceed to Test Step 3.

• NOT OK - The machine harness is not correct.

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

  STOP

Test Step 3. CHECK FOR A SHORT TO GROUND.

1. The disconnect switch remains OFF.

2. Disconnect the machine harness from all the electronic control modules that use the AVS data link.

3. At the machine harness connector for the ECM, measure the resistance between frame ground and the circuits of the AVS data link, contacts 9 (wire 893-GN(Green)) and 3 (wire 892-BR(Brown)).

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• YES - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to test step 4.

• NO - The resistance is less than 5000 ohms. The machine harness has failed. There is a short between the frame ground and the AVS data link circuit in the machine harness.

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

  STOP

Test Step 4. CHECK FOR A SHORT TO THE +BATTERY.

1. The disconnect switch remains OFF.

2. All related control modules remain disconnected from the machine harness.

3. At the machine harness connector for the ECM, measure the resistance between the +battery circuit 1 (wire 164-WH(White)) and the circuits of the AVS data link, contacts 9 (wire 893-GN(Green)) and 3 (wire 892-BR(Brown)).

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to Test Step 5.

• NOT OK - The resistance is less than 5000 ohms. The machine harness has failed. There is a short between the +battery and the AVS data link circuit in the machine harness.

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

  STOP

Test Step 5. CHECK FOR AN OPEN HARNESS.

1. The disconnect switch remains OFF.

2. All related control modules remain disconnected from the machine harness.

3. Check the continuity of the AVS data link circuit in the machine harness.

4. Measure the resistance from the connector contacts 9 (wire 893-GN(Green)) and 3 (wire 892-BR(Brown)) of the ECM to the connector for each of the related electronic control modules.

Expected Result:

The resistance is less than 5 ohms.

Results:

• YES - The resistance is less than 5 ohms. The AVS data link circuit in the machine harness is correct.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code indicator is illuminated for this diagnostic code. If the cause of the diagnostic code is not found, replace the MIDS ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NO - The resistance is greater than 5 ohms. The machine harness has failed. The AVS data link circuit is open in the machine harness.

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

  STOP