October 30: LEMON manuals on a temporary server, it is slow and having issues, download the manuals you need! Later in November we will switch back to the fast server.

Self-Diagnostic System: Summary

If no hard fault codes are present, driveability symptoms exist or intermittent DTC(s) exist, proceed to TROUBLE SHOOTING - NO CODES - TRUCKS article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.