For those with a remote starter on your Lexus, are any of you configured to enable rear defrost either automatically after start, or via separate button on remote?

I'd like to know if this is possible to wire into a 1990 LS400--although I think it would be similar for most all Lexus since the rear defrost button is integrated in to the climate control panel.

Think I can just tap into the rear defrost output wire coming out of the back of the control unit?

 

I've never seen it done, since the rear defrost must be manually activated after the car is started. That said, you're probably on the right tract of tapping into the output wire, it might work if you can find a way to send a signal through the remote to just that wire.

 

could possibly work fine using a single SPST or SPDT relay.

 

The power wouldn't go to the defrost circuit until the car has been started remotely anyway, so that's not the issue--the real issue is how to hijack the signal and get the circuit to power on without having to crack open the HVAC box.

I'm guessing it's a really simple solution--either way, I'll be getting in there this weekend, hopefully.

 

well you'll have to hook up the second ign. switch just to get the r. defrost to get power once u autostart it(now i might be wrong..seeing i never sat in my car and pressed the button to see) with that said...your radio will also come on so dont leave it up too loud..lol...but i would guess youll have to hook up a wire(pos or neg)from your alarm to the output side of the r.defrost button. Get a fluke type of multimeter and find out which side only have power once u press the button(im guessing one side should always be "hot" if its a pos system..) and hook your wire up to that wire. I think the timer on the r.defrost is very important tho..thats why its on there..so you dont burn up the heating elements...

but to b honest..i just blast my heat in my tahoe(dont have a autostart on my lexus yet) and by the time i go out to leave i can wipe my rear barn doors off with my hands

 

CJONES--that's what I was planning on doing in terms of probing for a hot wire coming off the rear control box.

I used to just blast the heat on my Civic, but I figured since I'll have an extra 200mA neg-trigger output on the Viper 160XV, I'll try to do it right and run the defrost control if I can tap into the car's system successfully.

Besides, the goal is *no hands on the cold car*! LOL.