Mirror Heater does not Operate with Rear Defogger Switch: Description

The mirror heater operation is linked with the defogger system or wiper and washer system.

Defogger linked function:

When the window defogger switch, which is built into the multi-display assembly*1 or integration control and panel*2, is operated, the operation signals are transmitted to the A/C amplifier assembly through AVC-LAN and BEAN. When the A/C amplifier assembly receives the signals, it turns on the heater mirror relay to operate the mirror heater. When the defogger switch is turned off, the mirror heater also turns off simultaneously.

Wiper linked function:

When the rain sensor detects raindrops while the windshield wiper switch assembly is in the AUTO position, the rain sensor sends a wiper operation request signal to the A/C amplifier assembly. When the A/C amplifier assembly receives the wiper operation request signal, it controls the heater mirror relay to operate the mirror heater. After the request signal from the rain sensor stops and 15 minutes elapses, the A/C amplifier assembly turns off the heater mirror relay to turn off the mirror heater.
When the windshield wiper switch assembly is moved to the INT, LO, HI or MIST position, the windshield wiper switch assembly sends a switch position signal to the A/C amplifier. When the A/C amplifier receives this signal, it controls the heater mirror relay to operate the mirror heater. After the switch position signal from the windshield wiper switch assembly stops and 15 minutes elapses, the A/C amplifier assembly turns off the heater mirror relay to turn off the mirror heater.

NOTE:

The power mirror control system is a part of the multiplex communication system. This system features shared communication wiring that reduces the wiring complexity of the communication lines. The first step in any repair is to confirm the proper operation of the communication system. Proceed with troubleshooting after the communication has been verified (See Multiplex Communication System. Refer to HOW TO PROCEED WITH TROUBLESHOOTING ).
The mirror heater operation is linked with the defogger system or wiper and washer system. Confirm that these systems are operating normally before starting the inspection.

*1: w/ LEXUS Navigation system
*2: w/o LEXUS Navigation system