988G Wheel Loader Electrohydraulic System Caterpillar

Illustration 1	g00837624
Schematic of the Circuit for the Harness Code Plug

This diagnostic code is recorded when the implement ECM determines that the attachment code has been changed in the Caterpillar Monitoring System.

The attachment code is stored by the Caterpillar Monitoring System. The attachment code is used to identify the attachments on a machine. The attachment code tells the following modules the physical limits of the machine: implement ECM, power train ECM and engine ECM.

The possible causes for this diagnostic code are listed:

• The harness code that is received from the Caterpillar Monitoring System is invalid. This invalid code is obtained through the CAT Data Link.

• The wrong wire for the harness code (wire 270-BK, 271-BK, 272-BK, 273-BK, 274-BK or 275-BK) is open or shorted to ground.

• The wrong harness code plug is installed.

• The ECM has failed. This is unlikely.

System Response:

The machine response is listed:

• Machine operation is not affected.

Note: An incorrect harness code that is connected to the Caterpillar Monitoring System can cause the CID 0650 FMI 11 to be recorded. Ensure that the CID 0650 FMI 11 is on hold and that the diagnostic code indicator shows "SERV CODE". This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. When the procedure is completed, clear the created diagnostic codes.

Test Step 1. CHECK THE MACHINE CODE OF THE MONITORING SYSTEM.

1. Turn the key start switch to the ON position.

2. Enter harness code mode (Mode 1) of the Caterpillar Monitoring System.

3. Check that the machine code that is showing matches the sales model. The machine code for 834G is 28. The machine code for 836G is 29. The machine code for 988G is 47.

Expected Result:

The machine code that consists of two digits should match the sales model.

Results:

• YES - The machine code is correct for the sales model. Proceed to test step 2.

• NO - The machine code is not correct for the sales model.

  Repair: The harness code plug for the monitoring system is not correct. Repair the harness code plug of the monitoring system or replace the harness code plug with a correct plug. See Service Manual, SENR1394, "Caterpillar Monitoring System".

  Stop.

Test Step 2. CHECK THE HARNESS CODE PLUG FOR THE CONFIGURATION.

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

2. Remove the harness code plug for the configuration from the harness. The harness code plug for the configuration is located near the Caterpillar Monitoring System.

3. Inspect the harness code plug for corroded connector contacts. If necessary, clean the connector contacts.

4. Measure the resistance between contact 7 of the harness code plug and each of the other contacts. Some of the spaces for the contacts in the plug are intentionally empty. Refer to illustration 1.

Expected Result:

The resistance measurement is correct.

Results:

• YES - The resistance measurement is correct for each circuit. The harness code plug is correct. Proceed to test step 3.

• NO - The resistance measurement is not correct for one or more circuits.

  Repair: Repair the harness code plug or replace the harness code plug. Verify that the harness corrects the problem.

  Stop.

Test Step 3. CHECK THE HARNESS.

1. The harness code plug remains disconnected from the machine harness.

2. The key start switch remains in the OFF position.

3. Disconnect the machine harness from the Caterpillar Monitoring System.

4. Measure the resistance for each wire for the harness code plug. Check the resistance from the connector of the harness code plug to the ECM. The wires for the harness code plug are listed: 270-BK, 271-BK, 272-BK, 273-BK, 274-BK and 275-BK.

Expected Result:

Each wire for the harness code plug should have less than 5 ohms of resistance.

Results:

• OK - The wiring for the harness code plug is correct. Proceed to test step 4.

• NOT OK - The wiring for the harness code plug is NOT correct.

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

  Stop.

Test Step 4. CHECK IF THE DIAGNOSTIC CODE REMAINS.

1. Turn the key start switch to the OFF position. Clean the contacts of the harness connectors.

2. Reconnect all harness connectors.

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

4. Enter the service mode of the Caterpillar Monitoring System and clear all inactive diagnostic codes.

5. Operate the machine.

6. Check whether CID 0650 FMI 11 is present. When the diagnostic code is present, "SERV CODE" is showing.

Expected Result:

The CID 0650 FMI 11 is NOT present. "SERV CODE" is NOT showing.

Results:

• OK - The CID 0650 FMI 11 is NOT present. The "SERV CODE" is NOT showing. 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.

• NOT OK - The diagnostic code has not been corrected.

  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.