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 switch "OFF"

Refer to "Shop Manual" and disconnect brake switch connector.

Ignition switch "ON"

Measure the voltage between Pin No. 1 (Brake switch power) terminal of brake switch harness connector and chassis ground.

Measure the voltage between Pin No. 3 (Brake lamp switch power) terminal of brake switch harness connector and chassis ground.

Is the measured value within specification?

	▶ Go to "Signal Circuit Inspection" procedure.
	▶ Repair open or short in circuit and then go to "Verification of vehicle Repair" procedure.

Ignition "OFF"

Disconnect battery (-) cable.

Refer to "Shop Manual" and disconnect Brake Switch and ECM/PCM connector.

Measure the resistance between Pin No. 2 (Brake switch) terminal of brake switch harness connector and Pin No. 23 (Brake switch) terminal of ECM/PCM harness connector.

Measure the resistance between Pin No. 4 (Brake lamp switch) terminal of brake switch harness connector and Pin No. 12 (Brake lamp switch) terminal of ECM/PCM harness connector.

Is the measured value within specification?

	▶ Go to "Component Inspection" procedure.
	▶ Repair open or short in circuit and then go to "Verification of vehicle Repair" procedure.