Field Service Mode Check

1. Ground diagnostic test terminal.
2. Operate engine at 1400-2000 RPM for two minutes and note ``Check Engine'' light.
3. If ``Check Engine'' light flashes approximately one time per second, the fuel system is functioning properly. Refer to ``Erratic or Intermittent Check Engine Light'' in HOW TO RUN TESTS, READ & EXTRACT CODES.
4. If ``Check Engine'' light flashes approximately 21/2 times per second, refer to ``Code 13 Oxygen Sensor Circuit.''
5. If ``Check Engine'' light does not illuminate or only lights infrequently, refer to ``Code 44 Lean Exhaust Indication.''
6. If ``Check Engine'' light stays lit for extended periods, refer to ``Code 45 Rich Exhaust Indication.''
7. If a Code 12 is displayed, refer to ``Crank Signal Circuit Check.''