ENGINE AR-PRIMARY 5251995 - Caterpillar

Table 1
Troubleshooting Test Steps Values Results
1. Check Connectors for Moisture and Corrosion
A. Inspect all the harnesses. Ensure that the routing of the wiring harness allows the wires to enter the face of each connector at a perpendicular angle. Otherwise, the wire will deform the seal bore. This situation can create a path for the entrance of moisture. Verify that the seals for the wires are sealing correctly.
B. Ensure that the sealing plugs are in place. If any of the plugs are missing, replace the plug. Ensure that the plugs are inserted correctly into the connector. Refer to Illustration 2.
C. Disconnect the suspect connector and inspect the connector seal. Ensure that the seal is in good condition. If necessary, replace the connector.
D. Thoroughly inspect the connectors for evidence of moisture entry.
Note: Some minor seal abrasion on connector seals is normal. Minor seal abrasion will not allow the entry of moisture.
If moisture or corrosion is evident in the connector, the source of the moisture entry must be found and repaired. If the source of the moisture entry is not repaired, the fault will recur. Simply drying the connector will not rectify the fault. Check the following items for the possible moisture entry path:
Missing seals
Incorrectly installed seals
Nicks in exposed insulation
Improperly mated connectors
Moisture can also travel to a connector inside a wire. If moisture is found in a connector, thoroughly check the connector harness for damage. Also check other connectors that share the harness for moisture.
Note: The ECM is a sealed unit. If moisture is found in an ECM connector, the ECM is not the source of the moisture. Do not replace the ECM.
Harness, connectors, and seals are OK. Result: A fault has been found with the harness or the connectors.
Repair: Repair the connectors or the wiring, as required. Ensure that all the seals are correctly installed. Ensure that the connectors have been reattached.
If corrosion is evident on the pins, sockets or the connector, use only denatured alcohol to remove the corrosion. Use a cotton swab or a soft brush to remove the corrosion.
If moisture was found in the connectors, run the engine for several minutes and check again for moisture. If moisture reappears, the moisture is wicking into the connector. Even if the moisture entry path is repaired, replacement of the wires may be necessary.
Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
Result: The harness, connectors, and seals are in good condition.
Proceed to Test Step 2.
2. Check the Wires for Damage to the Insulation
A. Carefully inspect each wire for signs of abrasion, nicks, and cuts.
Inspect the wires for the following conditions:
Exposed insulation
Rubbing of a wire against the engine
Rubbing of a wire against a sharp edge
B. Check all the fasteners for the harness and the strain relief components on the ECM to verify that the harness is correctly secured. Also check all the fasteners to verify that the harness is not compressed. Pull back the harness sleeves to check for a