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Computer Power and Ground Circuits -- Outline

POWER AND GROUND
ECM (Engine Control Module) ground (Analogue)

- If the circuit has an open, engine hard starting and rough idle will be caused and Trouble Code Nos. 09,11,12,13, 20 and 23 will be output.

ECM ground (Fuel injector)
- An open circuit will not produce any symptom.
- If the ECM ground (Output devices) circuit also has an open, the engine will not start.

ECM ground (Output devices)
- An open circuit will not produce any symptom.
- If ECM ground (Fuel injector) circuit also has an open, the engine will not start.

ECM ground (System)
- An open circuit will not produce any symptom.

Main Relay (Battery power)
- If the circuit is shorted, the EGI INJ fuse (30A) will burn out.

Room Fuse (ECM memory power)
- If the circuit is open, the ECM memory function will not operate, and trouble codes for intermittent malfunctions will not be indicated. Also, the learning control will be canceled, but will not produce any particular symptom.
- If the circuit is shorted, the ROOM fuse (15A) will burn out.