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| Illustration 1 | g00842126 |
Schematic of the Circuit for the Harness Code Plug | |
This diagnostic code is recorded when the power train ECM does not recognize the attachment code that is being sent by the Caterpillar Monitoring System.
The possible causes for this diagnostic code are listed:
- The incorrect harness code plug is installed.
- Short in the harness code plug.
- Open in the harness code plug.
- Short in the harness between the harness code plug and the Caterpillar Monitoring System.
- Open in the harness between the harness code plug and the Caterpillar Monitoring System.
System Response:
The machine response is listed:
- The operator maintains all functions of the transmission control that were derived from the last valid reading of the harness code.
Note: Ensure that the diagnostic code indicator is active and that the diagnostic code is active.
Test Step 1. CHECK THE HARNESS CODE PLUG
- Disconnect the harness code plug from the harness.
- Check the continuity against the electrical schematic.
Expected Result:
The continuity matches the electrical schematic.
Results:
- YES - The continuity matches the electrical schematic. Proceed to test step 2.
- NO - The continuity does not match the electrical schematic.
Repair: Repair the harness code plug or replace the harness code plug.
Stop.
Test Step 2. CHECK THE HARNESS FOR AN OPEN CIRCUIT
- Disconnect the harness from the rear of the Caterpillar Monitoring System.
- Check the continuity between the Caterpillar Monitoring System and the circuits for the following wires: 270-BK, 271-BK, 272-BK, 273-BK, 274-BK and 275-BK.
Expected Result:
The resistance is less than 5 Ohms for each circuit.
Results:
- YES - The resistance is less than 5 Ohms for each circuit. Proceed to test step 3.
- NO - The resistance is greater than 5 Ohms.
Repair: The harness has failed. There is an open circuit in the harness. Repair the harness or replace the harness.
Stop.
Test Step 3. CHECK THE HARNESS FOR A SHORT CIRCUIT
- Check for shorts at either end of the harness of the following circuits: 270-BK, 271-BK, 272-BK, 273-BK, 274-BK and 275-BK.
Expected Result:
The resistance is greater than 5000 Ohms for each pair of circuits.
Results:
- YES - The resistance is greater than 5000 Ohms for each pair of circuits. Proceed to test step 4.
- NO - The resistance is less than 5000 Ohms for each pair of circuits.
Repair: There is a short in the harness. Repair the harness or replace the harness.
Stop.
Test Step 4. CHECK IF THE DIAGNOSTIC CODE REMAINS
- Reconnect the harness code plug.
- Reconnect the connector for the Caterpillar Monitoring System.
- Ensure that the diagnostic code is still active.
Expected Result:
The diagnostic code is no longer active.
Results:
- YES - The diagnostic code is no longer active.
Repair: The diagnostic code no longer exists. The diagnostic code was caused by a loose connection.
Stop.
- NO - The diagnostic code is still active.
Repair: It is unlikely that the Caterpillar Monitoring System has failed. Exit this troubleshooting procedure. Perform this test 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.