CT660 CX31 and CX31 HT On Highway Truck Power Train Electronic Control System Caterpillar

Use the following steps to help determine if the connector is the cause of the problem. If a problem is found in the electrical connector, repair the connector and verify that the problem has been corrected.

The following background information is related to this procedure:

Many of the operational procedures and the diagnostic trouble code procedures in this troubleshooting guide will instruct you to check a specific electrical connector.

Intermittent electrical problems are often caused by poor connections. Always check for an active diagnostic trouble code before breaking any connections. Also, always check for an active diagnostic trouble code after the connector is reconnected in order to verify that the problem disappears.

Simply disconnecting the connectors and then reconnecting the connectors can temporarily solve a problem at times. If this occurs, likely causes are loose terminals, bent terminals, improperly crimped terminals, corrosion, or harness routing that is improper.

The original source of the problem must then be identified in order to ensure that the problem does not reoccur.

Follow this procedure to thoroughly inspect the connectors in order to determine if the connectors are the cause of the problem.

Illustration 1	g00820688
(1) Correctly Routed Harness (2) Correctly Inserted Plug (3) Incorrectly Routed Harness (4) Incorrectly Inserted Plug

Illustration 2	g00690571
Proper Installation of Plug

Illustration 3	g00828600
DT Type sealing plug The 8T-8729 Connector Pin (2) and the 8T-8730 Connector Socket (1) is designed to accept only one 16/18 AWG wire. Do not insert multiple wires of a smaller wire size. Using two 24 AWG wires is an example of this method that is incorrect. The 9W-0852 Connector Pin and the 9W-0844 Connector Socket are designed to accept only one 14 AWG wire. Do not insert multiple wires of a smaller wire size. Using two 20 AWG wires is an example of this method that is incorrect.

1. CHECK THE CONNECTORS.

   1. Ensure that the connector is properly locked. Also, ensure that the two halves of the connector cannot be pulled apart.

   2. Verify that the latch tab of the connector is properly latched. Verify that the latch tab of the connector is fully latched.

      Expected Result: The connector will securely lock. The connector and the locking mechanism are without cracks or breaks.

      Results:

      OK - The connector will securely lock. The connector and the locking mechanism are without cracks or breaks. Proceed to test step 2.

      NOT OK - A problem exists with the connector.

      Repair: Repair the connector or replace the connector, as required.

      STOP.

2. CHECK THE ALLEN HEAD SCREW ON THE HARNESS CONNECTOR OF THE ECU.

   1. Ensure that the connector bolt is properly tightened. Be careful not to tighten the bolt too much. The bolt may break.

   2. Do not exceed 6.0 N·m (53.0 lb in) of torque on the connector bolt of the harness when the connector is being installed on the ECU.

      Expected Result: The harness connector is secure and the connector bolt of the ECU is properly torqued.

      Results:

      OK - The harness connector is secure and the connector is properly torqued. Proceed to test step 3.

      NOT OK - A problem exists with the connector.

      Repair: Secure the harness connector of the ECU. Ensure that the connector bolt is properly torqued.

      STOP.

3. PERFORM A PULL TEST ON EACH CONNECTOR CONTACT.

   1. Each connector contact should withstand 45 N (10 lb) of pull. Each wire should remain in the connector body. This test checks whether the wire was properly crimped in the contact and whether the contact was properly inserted into the connector.

   2. The DT connectors use an orange wedge to lock the terminals in place.

   3. Check in order to ensure that the orange wedge is not missing and that the orange wedge is installed properly on the DT connectors.

      Note: Connector contacts should ALWAYS be crimped onto the wires by using a Crimp Tool. Do not solder the terminals. Use the proper Crimp Tool.

      Expected Result: Each connector contact should withstand 45 N (10 lb) of pull. Each wire remains in the connector body.

      Results:

      OK - Each connector contact withstands 45 N (10 lb) of pull. Each wire remains in the connector body. Proceed to test step 4.

      NOT OK - A problem exists with the connector.

      Repair: Repair the wiring or replace the connector contact.

      STOP.

4. CHECK THE WIRES FOR NICKS OR ABRASIONS IN THE INSULATION.

   1. Carefully inspect each wire for signs of abrasion, nicks, or cuts.

      The following areas are locations that should be checked:

      • Exposed insulation

      • Points of rubbing wire

   2. Check all of the hold down clamps for the harness in order to verify that the harness is properly clamped. Also check all of the hold down clamps for the harness in order to verify that the harness is not compressed by the clamp. Pull back the harness sleeves in order to check for a flattened portion of wire. The flattened portion of wire is caused by the clamp that holds the harness.

      Expected Result: The wires are free of abrasion, nicks, or cuts and the harness is properly clamped.

      Results:

      OK - The wires are free of abrasion, nicks, or cuts and the harness is properly clamped. Proceed to test step 5.

      NOT OK - A problem exists with the wiring.

      Repair: Repair the wires or replace the wires, as required.

      STOP.

5. CHECK THE CONNECTORS FOR MOISTURE OR CORROSION.

   1. Ensure that the connector seals and the white sealing plugs are in place. If any of the seals or plugs are missing, replace the seal or plug. If necessary, replace the connector.

   2. Check all of the wiring harnesses in order to verify that the harness does not make a sharp bend out of a connector. This will deform the connector seal and will create a path for the entrance of moisture. See Illustration 1.

      Note: It is normal to see some minor seal abrasion on the ECU connector seals. Minor seal abrasion will not allow the entry of moisture.

   3. Thoroughly inspect ECU connectors for evidence of moisture entry. 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 problem will reoccur. Simply drying the connector will not fix the problem. Likely paths for the entrance of moisture are from missing seals, improperly installed seals, nicks in exposed insulation, and improperly mated connectors.

      Note: Moisture can also travel from one connector through the inside of a wire to the ECU Connector. If moisture is found in the ECU connector, thoroughly check all connectors and wires on the harness that connect to the ECU. The ECU is not the source of the moisture. Do not replace an ECU if moisture is found in either ECU connector.

      Note: If corrosion is evident on the contacts or the connector, use only denatured alcohol to remove the corrosion. Use a cotton swab or a soft brush to remove the corrosion. Do not use cleaners that contain trichloroethylene because trichloroethylene may damage the connector.

      Expected Result: All of the connectors should be completely coupled and all of the seals should be completely inserted. The harness and the wiring should be free of corrosion, moisture, abrasion or pinch points.

      Results:

      OK - All of the connectors are completely coupled and all of the seals are completely inserted. The harness and the wiring are free of corrosion, moisture, abrasions, or pinch points. Proceed to test step 6.

      NOT OK - A problem exists with the connector, the wiring, or the wiring harness. Moisture is present.

      Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem by operating the machine for several minutes and by checking again for moisture.

      STOP.

6. INSPECT THE CONNECTOR CONTACTS.

   1. Verify that the contacts are not damaged. Verify that the contacts are properly aligned in the connector and verify that the contacts are properly located in the connector.

      Expected Result: The contacts are properly aligned and the contacts appear undamaged.

      Results:

      OK - The contacts are properly aligned and the contacts appear undamaged. Proceed to test step 7.

      NOT OK - A problem exists with the connector contacts.

      Repair: Repair the contacts and wiring and/or replace the contacts and wiring.

      STOP.

7. CHECK THE FIT OF THE CONTACTS.
   Show/hide table

   Illustration 4	g00838765
   Retention of the Connector (1) Pin Contact (2) Socket Contact

   Note: This is especially important for intermittent problems.

   1. Use a new pin contact. Insert the pin contact into each socket contact one at a time in order to check for a good grip on the pin contact by the socket contact.

   2. Use a new socket contact. Insert the socket contact over each pin contact one at a time in order to check for a good grip on the pin contact by the socket contact. The pin contacts are located on the mating side of the connector.

   3. The connector contact should stay connected when the connector is held in the position shown in Illustration 4. The connector contact is the pin contact or the socket contact.

      Expected Result: The pin contacts and the socket contacts appear to be OK.

      Results:

      OK - The pin contacts and the socket contacts appear to be OK. STOP.

      NOT OK - A problem exists with the connector terminal.

      Repair: Replace the connector contact.

      STOP.