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 connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, 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 "OFF".

Disconnect Brake Lamp Relay(HAC relay).

Ignition "ON" & Engine "OFF".

Measure voltage between power terminal of brake lamp relay(HAC relay) harness connector and chassis ground.

Is the measured value within specifications ?

	▶ Go to "Control Circuit Inspection" procedure.
	▶ Check for open or blown fuse referring to "Circuit Diagram". ▶ Repair open or short in power circuit between battery and HECU harness connector and then, go to "Verification of vehicle Repair" procedure.

IG "OFF".

Disconnect Brake Lamp Relay(HAC relay) and HECU connector.

Measure resistance between control terminal of brake lamp relay(HAC relay) harness connector and brake lamp control terminal of HECU harness connector.

Is the measured value within specifications ?

	▶ Go to "Short Check" procedure.
	▶ Repair open in control circuit between the brake lamp relay and HECU and then, Go to "Verification of vehicle Repair" procedure.

IG "OFF".

Disconnect Brake Lamp Relay(HAC relay) and HECU connector.

Measure resistance between control terminal of brake lamp relay(HAC relay) harness connector and chassis ground.

Is the measured value within specifications ?

	▶ Substitute with a known-good Brake Lamp Relay(HAC relay) and check for proper operation. If problem is corrected, replace Brake Lamp Relay(HAC relay)and then go to "Verification of Vehicle Repair" procedure.
	▶ Repair short in control circuit between Brake Lamp Relay(HAC relay) and HECU, and then go to "Verification of vehicle Repair" procedure.