Diagnostic Procedure

NOTE: DO NOT skip any steps in self-diagnostic tests or incorrect diagnosis may result.

Always perform a visual inspection before attempting to diagnose engine control system problems. See VISUAL INSPECTION. Enter on-board diagnostics, and retrieve fault code(s). See ENTERING ON-BOARD DIAGNOSTICS. If fault codes are not present and/or DRB-II (Diagnostic Readout Box II) is used, proceed to one of the following tests:

Go to TEST NS-1A (QUALIFYING NO START CONDITION) if a no-start condition exists or engine stalls after start-up. Perform indicated VERIFICATION TEST after repairs have been made.
Go to TEST DR-1A (CHECKING SYSTEM FOR FAULTS) if engine runs but has performance problems. Perform indicated VERIFICATION TEST after repairs have been made.
Go to TEST NF-1A (NO FAULT TEST CODE MENU) if a driveability problem exits and no fault codes are present. Perform indicated VERIFICATION TEST after repairs have been made.