wiring a hrw

[xantiaman]

hi all
im having problems with my heated rear window not working,i know its not the window itself as when the temp is low it comes on automatically and clears the screen lovely it just wont work on the switch,it beeps but no liight on the switch itself.i have changed the a/c panel already as i was having probs with some functions on that and as before the hrw still doesnt work by switch.can someone tell me how to wire it up to a seperate switch?will it need a relay as i know hrw's draw a lot of current.im no electrician but with good instructions i am quite capable.thanks

[Greeners]

You can't simply wire it in, as it's controlled by the ECU.

I would start by disconnecting the battery to reset the ECU...(check you have a radio code is required and follow the satnav shut down procedure if fitted)

If the HRW comes on automatically, then the wiring and switch are fine, and the problem lies elsewhere.

[xantiaman]

ok i will try that,i was thinking about leaving the existing wiring connected and maybe just piggy backing new wiring to a seperate switch so i could operate the hrw at will but obviously it seems this will cause problems.thanks for the reply

[Cymrudragon]

looking at the diagram the switch has a lo diode in the swich with 3 pins one is earth one is lod from bcu...other is a switch ......looks like the R2 relay contact may be the problem or the solinoid within .....i think the switch within the car is a ovrride function.....as you are geting power to the screen and looking at the engine fuse box r2 relay (87) is a direct feed vear filtter......so eather contact within the switch in car or contact within the relay (engine fuse box......or poss earth to in car switch.........

[xantiaman]

i dont really understand much of that but i have just been out and identified the relay you mentioned and swapped it with the identical one below it and still no hrw.

[xantiaman]

is there not a seperate fuse for the hrw i have looked at the diagram in the owners manual but cant see 1.