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 a TCL problem.

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