The DDT communicates directly to the Timing Control Module (TCM) over the CAT Data Link. The DDT is used to display the status information for the timing control system. The DDT displays diagnostic codes when faults occur. The DDT enables calibration and programming of the system in order to match the performance requirements.
The DDT operates on battery voltage. The battery voltage is supplied to the DDT when the voltage is supplied to the TCM.
Two wires are used between the DDT and the TCM in order to communicate.
The DDT will diagnose faults for software, internal failures and programming errors. The faults are displayed on the DDT.
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| Illustration 1 | g00665238 |
Test Step 1. Check for Connector Damage.
- Remove power from the timing control system.
- Check the connector for the TCM. Refer to Troubleshooting, "Inspecting Electrical Connectors".
- Check the harness and the connectors for the DDT.
Expected Result:
The connectors and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.
Results:
- OK - The connectors and wiring are in good condition. Proceed to test step 2.
- Not OK - The connectors and/or wiring require service.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
Stop.
Test Step 2. Check the Service Program Module (SPM).
- Disconnect the DDT from the harness.
- Check the Service Program Module (SPM) in the DDT. Refer to Tool Operating Manual, SEHS8806, "Using the NEXG4511 Industrial Applications DDT Function Service Program Module".
Expected Result:
The SPM is correct for the timing control system.
Results:
- OK - Proceed to test step 3.
- Not OK -
Repair: Remove the SPM and reinstall the SPM. If necessary, replace the SPM.
Stop.
Test Step 3. Check for an Open Circuit.
- Disconnect the TCM from the engine harness.
- Disconnect the harness for the DDT from the engine harness.
- Use the 400 ohm scale to measure the resistance at the engine harness.
- Measure the resistance from the timing control harness connector (TCHC) to the connector for the DDT (DDTC).
Show/hide table
Table 1 TCHC Pin DDTC Pin M A N B W C X D
- Measure the resistance from the timing control harness connector (TCHC) to the connector for the DDT (DDTC).
Expected Result:
The resistance is less than 2 ohms.
Results:
- OK - The resistance is correct. Proceed to test step 4.
- Not OK - There is a problem in the wiring.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
Stop.
Test Step 4. Check for a Short Circuit.
- Use the 4000 ohm scale to measure the resistance at the engine harness.
- Measure the resistance from pin W (TCHC) to all of the other pins.
- Measure the resistance from pin X (TCHC) to all of the other pins.
Expected Result:
The resistance is greater than 2000 ohms.
Results:
- OK - The resistance is correct. Proceed to test step 5.
- Not OK - There is a problem in the wiring.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
Stop.
Test Step 5. Check the Harness of the DDT for an Open Circuit.
- Disconnect the harness of the DDT from the engine harness.
- Disconnect the DDT from the harness.
- Use the 4000 ohm scale to measure the resistance at the harness for the DDT.
Expected Result:
The resistance is less than 2 ohms.
Results:
- OK - The resistance is correct. Proceed to test step 6.
- Not OK - There is a problem in the wiring.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
Stop.
Test Step 6. Check for a Short Circuit.
- Use the 4000 ohm scale to measure the resistance between all of the pins at the connectors for the STC and the DDTC.
Expected Result:
The resistance is greater than 2000 ohms.
Results:
- OK - The problem is undetermined.
Repair: Reset the system and troubleshoot any active diagnostic codes.
Stop.
- Not OK - There is a problem in the wiring.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
Stop.