PaulMc said:

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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Ctrl_alt_del said:

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?

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sierrafery said:

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

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sierrafery said:

still no reaction if you push the demist button on the aircon?

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Ctrl_alt_del said:

No, I’ll need to check fuses and nano com again tomorrow. Too dark now

The switch isn’t illuminating with the lights on either.

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sierrafery said:

still no reaction if you push the demist button on the aircon?

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Ctrl_alt_del said:

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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