Diagnostic Troubleshooting Strategy

Use these steps to plan your diagnostic strategy. If you follow them carefully, you will check most of the possible causes of an auto-cruise control system problem.

1. Gather information from the customer.
2. Verify that the condition described by the customer exists.
3. Check the vehicle for any auto-cruise control system DTC. (Refer to DIAGNOSTIC FUNCTION - HOW TO READ AND ERASE DIAGNOSTIC TROUBLE CODES ).
4. If you can verify the condition but no auto-cruise control system DTCs are set, and the malfunction may be intermittent. (Refer to HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS - HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
5. If you can verify the condition but there are no auto-cruise control system DTCs, or the system cannot communicate with scan tool MB991958 (MUT-III sub assembly), and find the fault. (Refer to SYMPTOM CHART ).
6. If there is an auto-cruise control system DTC, record the number of the code, then erase the code from vehicle memory using the scan tool. (Refer to DIAGNOSTIC FUNCTION - HOW TO READ AND ERASE DIAGNOSTIC TROUBLE CODES ).
7. Re-create the auto-cruise control system DTC set conditions to see if the same auto-cruise control system DTC will set again.
   • If the same auto-cruise control system DTC sets again, perform the diagnostic procedures for the set code. (Refer to DIAGNOSTIC TROUBLE CODE CHART ).