Diagnostic Circuit Check
NOTE:
Test numbers refer to test numbers on diagnostic chart.
Diagnostic circuit check is the starting point for identifying a problem caused by the fuel injection system.
- If CHECK ENGINE light illuminates with ignition on and engine off, it confirms battery and ignition voltage to ECM.
- ECM uses the CHECK ENGINE light to flash 2-digit codes. All fault codes stored in ECM will be flashed 3 times. The lowest code number will be flashed first. If no fault codes are stored, Code 12 will flash (until fuse is removed from fuse box), indicating ECM diagnostics are working. If engine starts, go to TESTS W/O CODES article in the ENGINE PERFORMANCE Section. If engine cranks but will not start, see BASIC TESTING article in the ENGINE PERFORMANCE Section.
- Record all fault codes. Go to appropriate code chart(s).