Illustration 1 | g00565044 |
System Schematic For CAT Data Link |
Note: Ensure that the "SERV CODE" indicator is ON.
This diagnostic code is recorded when the Main Display Module does not receive expected information. For example, the engine speed is not received from the engine ECM through the CAT Data Link. As a result of this diagnostic condition, the Display Area is dependent on the CAT Data Link for information that indicates abnormal values. The following items are possible causes of these readouts. The list is in order of probability.
- There is a poor electrical connection at the engine harness connector.
- The CAT data link circuit in the engine harness is shorted to ground.
- The CAT data link circuit in the engine harness is shorted to +Battery.
- The CAT data link in the engine harness is open.
- Another electronic module that also uses the CAT Data Link is having a problem: secondary ECM and CCM.
Note: Ensure that the desired diagnostic code (CID and FMI) is on hold. Ensure that the service code indicator shows "SERV CODE".
An electronic control module which uses the CAT data link is faulty. If the main display module was recently replaced, see Testing and Adjusting, "Main Display Module Initialization - Adjust".
- Check For Other Codes.
- Check other electronic control modules for a similar diagnostic code. If a similar diagnostic code is found, exit this test. Perform the corresponding procedures for the other diagnostic codes that are shown.
Expected Result: There are other diagnostic codes that are showing.
Results:
- OK: Exit this procedure and perform the other procedures for the diagnostic codes that are shown. STOP.
- Not OK: There are not any other diagnostic codes that are showing. Proceed to Step 2.
- OK: Exit this procedure and perform the other procedures for the diagnostic codes that are shown. STOP.
- Check other electronic control modules for a similar diagnostic code. If a similar diagnostic code is found, exit this test. Perform the corresponding procedures for the other diagnostic codes that are shown.
- Inspect The Harness Connectors.
- Turn the disconnect switch to the OFF position.
- Inspect the connections for the machine harness that are related to the CAT Data Link.
- Make sure that connectors are clean and tight.
Expected Result: The engine harness is correct.
Results:
- OK: The engine harness is correct. Proceed to Step 3.
- Not OK: The engine harness is not correct. Repair the engine harness or replace the engine harness. STOP.
- OK: The engine harness is correct. Proceed to Step 3.
- Check For A Short To Ground.
- The "ECS" switch remains in the OFF/RESET position.
- Disconnect the engine harness from all electronic modules that use the CAT data link.
- At the engine harness connector for the main display module, measure the resistance between battery ground and the CAT Data Link circuits (Contact 5 and Contact 14).
Expected Results: The resistance that is measured is less than 5000 ohms.
Results:
- OK: The resistance is less than 5000 ohms. The engine harness is faulty. There is a short between the battery ground and the CAT Data Link circuit in the engine harness. Repair the engine harness or replace the engine harness. STOP.
- Not OK: The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to Step 4.
- OK: The resistance is less than 5000 ohms. The engine harness is faulty. There is a short between the battery ground and the CAT Data Link circuit in the engine harness. Repair the engine harness or replace the engine harness. STOP.
- Check For A Short To The +Battery.
- The "ECS" switch remains in the OFF/RESET position.
- All related control modules remain disconnected from the machine harness.
- At the engine harness connector for the main display module, measure the resistance between the +Battery (contact 1) and the CAT Data Link circuits (contacts 5 and 14).
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 Step 5.
- Not OK: The resistance is less than 5000 ohms. The engine harness is faulty. There is a short between the +Battery and the CAT Data Link circuit in the machine harness. Repair the engine harness or replace the engine harness. STOP.
- OK: The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to Step 5.
- Check For An Open Harness.
- The "ECS" switch remains in the OFF/RESET position.
- All the related control modules remain disconnected from the machine harness.
- Measure the voltage from the connector for the main display module (contact 5 and contact 14) to the connectors for each of the related electronic control modules.
Expected Result: The resistance is less than 5 ohms.
Results:
- OK: The resistance is less than 5 ohms. The CAT Data Link circuit in the engine harness is correct. The main display module is faulty. Replace the main display module. See Testing and Adjusting, "Module - Replace". STOP.
- Not OK: The resistance is greater than 5 ohms. The engine harness is faulty. The CAT Data Link circuit is open in the engine harness. Repair the engine harness or replace the engine harness. STOP.
- OK: The resistance is less than 5 ohms. The CAT Data Link circuit in the engine harness is correct. The main display module is faulty. Replace the main display module. See Testing and Adjusting, "Module - Replace". STOP.