Computer Power and Ground Circuits -- Outline

Main Relay (Battery Power)
- If the circuit is open, the engine will not start.
- If the circuit is shorted, the EGI NJ fuse (40 A) will burn out.

Room Fuse (ECM Memory Power)
- If the circuit is open, the ECM memory function will not operate, and diagnostic 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 (15 A) will burn out.

Ground (Output Devices, Fuel Injector)
- If an output device or a fuel injector has an open ground circuit, no particular symptom will be produced.
- If a related output device and injectors both have open ground circuits, the engine will not start.

Ground (System, Analogue)
- An open circuit will not produce any symptom.

Terminal TEN (Data Link Connector)
- If the circuit is shorted, the opening amount of the idle air control valve will not change, causing hard starting and rough idle. The ignition timing will be fixed, causing lack of power and poor acceleration.
- If the circuit is shorted, the coolant fan operates whenever the throttle valve is opened (Ignition switch ON).

Terminal KLN (Data Link Connector 2)
- If both circuits are open or short, the NGS indicates "LINK COMMUNICATION ERROR".

Serial Line
- If each or both lines have an open or short, Diagnostic trouble Code No.P1 601 is output.