It appears to be within the engine bay fuse box. Relay 8


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The dash switch is a non-latching momentary switch, which switches a wire from the BCU to earth.

This signals the BCU to switch the heated windscreen relay's coil to earth, which it does for the timed period.

During the timed period, the BCU supplies a live to pin 5 of the dash switch, in order to illuminate the switch's tell-tale LED.

Check that the dash switch's earth, on pin 4, is OK - if the switch's night-time illumination works with sidelights switched on - then, the earth is OK.

You will also need to check that the BCU has the heated windscreen option enabled - you'll need an appropriate tool to do this - Nanocom, Hawkeye, etc...

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I am having the windscreen fitted next week, today I installed the switch to the top right above the heated rear switch, added relay to 8 and both 40amp fuses. I've enabled the BCU with NanoCom and saved. Would I expect the switch to iluminate without a screen connected or do I need to wait until circuit complete?
 
I am having the windscreen fitted next week, today I installed the switch to the top right above the heated rear switch, added relay to 8 and both 40amp fuses. I've enabled the BCU with NanoCom and saved. Would I expect the switch to iluminate without a screen connected or do I need to wait until circuit complete?
No need to have the screen connected, if everything is OK it should work anyway and you can check if you have voltage in the plugs
 
No need to have the screen connected, if everything is OK it should work anyway and you can check if you have voltage in the plugs
Will check again tomorrow, switch was not lighting up, did not illuminate with lights on like the others and did not have the red led lit when enabled with Nano com.
 
still no reaction if you push the demist button on the aircon?
Just want to check with you, I got the new Front Heated switch working and when I press the demist button on the Aircon now both the rear heated and front heated switch LED's flash together is that correct?
 

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