System outline

When power sw is at ig on position, turning on rear def sw on the steering wheel sends signal to a/c control assembly. Then a/c control assembly flows electricity in terminal rr def, which activates def relay and mirror heater relay. As a result, rear def sw and mirror heater is turned on.

Turning on rear def sw of multi-display sends signal to a/c control assembly. Then the same action follows as above. During rear window defogger and mirror heater in operation, signal is input in combination meter, lighting rear def indicator in combination meter.