Many malfunctions in the electrical system are caused by poor harness(es) 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 go to "Verification of Vehicle Repair" procedure
	▶ Go to "Power Circuit Inspection" procedure.

IG "OFF" and disconnect ECM connector.

IG "ON" and keep the brake taking off. (Measurement "A").

Measure the voltage between brake switch signal terminal of ECM harness connector and chassis ground.

Measure the voltage between brake lamp signal terminal of ECM harness connector and chassis ground.

Keep the brake stepping on.(Measurement "B")

Measure the voltage between brake switch signal terminal of ECM harness connector and chassis ground.

Measure the voltage between brake lamp signal terminal of ECM harness connector and chassis ground.

Is the measured voltage within specification?

	▶ Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
	▶ Go to "Check open in harness" as follows.

IG "OFF" and disconnect stop lamp switch and ECM connector.

Measure the resistance between brake switch signal terminal of ECM harness connector and brake switch signal terminal of Stop lamp switch harness connector.

Measure the resistance between brake lamp signal terminal of ECM harness connector and brake lamp signal terminal of Stop lamp switch harness connector.

Is the measured resistance within specification?

	▶ Go to "Check Battery voltage" procedure.
	▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure

IG "OFF" and disconnect stop lamp switch connector.

Measure the voltage between power supply terminals of stop lamp switch harness connector and chassis ground.

IG "ON".

Measure the voltage between power supply terminals of stop lamp switch harness connector and chassis ground.

Is the measured voltage within specification?

	▶ Substitute with a known - good stop lamp switch and check for proper operation. If the problem is corrected, replace stop lamp switch and go to "Verification of Vehicle Repair" procedure.
	▶ Check the fuse between battery and stop lamp switch. ▶ Repair open or short in power circuit of stop lamp switch and go to "Verification of Vehicle Repair" procedure.