Check Seat Heater Switch

1. Turn the ignition switch to ON.
2. Measure the voltage between the seat heater switch and chassis ground when turning the switch to a position other than OFF.

Connector & terminal 

LHD side seat 

(R42) No. 4 (+) - Chassis ground (-): 

RHD side seat 

(R45) No. 4 (+) - Chassis ground (-): 

Does the voltage fluctuate between 12 V ↔ 0 V?

• Yes  → Harness faulty, open circuit of heater or thermostat faulty.
• No  → Replace the seat heater switch.