Measure the voltage between harness connector terminal and chassis ground.
Connector & terminal
(B65) No. 1 (+) — Chassis ground (−):
Is the voltage 10 V or more?
• Check fuse No. 18 (in fuse & relay box).
• Check for open or short circuit in the harness between stop light & brake switch and fuse & relay box.
• Check the clutch switch and circuit.