Many malfunctions in the electrical system are caused by poor harness and terminals.

Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage.

Has a problem been found?

	▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
	▶ Go to "Power Circuit Inspection" procedure.

Ignition switch "OFF"

Refer to "Shop Manual" and remove the ECU Main 40A fuse.

Measure the voltage between engine control relay power terminal of ECU Main 40A fuse harness connector and chassis ground.

Fig.1) ECU Main fuse

Is the measured value withing specification?

	▶ Go to "Control Circuit Inspection" procedure.
	▶ Inspect and repair open or short in circuit, and then go to "Verification of Vehicle Repair" procedure.

Ignition switch "OFF"

Disconnect battery (-) cable.

Refer to "Shop Manual" and disconnect ECM and engine room junction box connector.

Measure the resistance between Pin No. 16 (Engine Control Relay) terminal of engine room junction box harness connector and Pin No. 89 (Engine Control Relay) terminal of ECM harness connector.

Is the measured value within specification?

	▶ Carefully re-do this troubleshooting guide steps. ▶ If no problems were found with the circuits or connectors, replace the Main Relay and go to "Verification of Vehicle Repair" procedure.
	▶ Inspect and repair open or short in circuit, and then go to "Verification of Vehicle Repair" procedure.