Heated rear screen!

[Tom]

The screen on the 205 doesnt work, and for a stripped car with holes in the floor, it wont stop steaming up. Anyway, found the wire for it, buuuuut it earths when you turn it on instead of being a hefty 12v. Check the wiring diagram and im pretty sure its not supposed to do that. So whats going on? I checked the relay and it clicks and i get continuity when i put 12v across it. So what could be going on?

[Tom]

Anyone? Im thinking the relay is dodgy or the 12v source isnt there and theres something so not cool going on behind the dash!

[Piggy]

check the 12v source for the relay...IE the power into the relay that needs to then go to the screen! (maybe just a fuse!?)

[Niall]

wiat so your saying the 12v goes straight to earth when you turn it on? If so, id be testing the relay to start with. If thats ok, someone has damaged a cable. have fun with that!

[Tom]

check the 12v source for the relay...IE the power into the relay that needs to then go to the screen! (maybe just a fuse!?)

That was my next plan.

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wiat so your saying the 12v goes straight to earth when you turn it on? If so, id be testing the relay to start with. If thats ok, someone has damaged a cable. have fun with that!

Yeah i put my meter on the wire for the heated screen and on an earth, and when i press the rear screen button its goes beeeeeeeeeeeeeeeeeeeeeeeeeep then stops when i flick it off. Giggidy.

[Niall]

Yeah i put my meter on the wire for the heated screen and on an earth, and when i press the rear screen button its goes beeeeeeeeeeeeeeeeeeeeeeeeeep then stops when i flick it off. Giggidy.

yeah...its supposed to do that lol

[Tom]

Ok now you've lost me. The heated rear screen is constanly earthed, then powered when you flick the switch, no? I get an earth on the power wire when i turn the screen on.

[Toms306]

That's how its supposed to be....power through the switch, via the screen and then earthed via the chassis back to the battery.... You're putting the multimeter between power and earth so it will be live until switched off which breaks the circuit.

[Niall]

That's how its supposed to be....power through the switch, via the screen and then earthed via the chassis back to the battery.... You're putting the multimeter between power and earth so it will be live until switched off which breaks the circuit.

This.

You need to take the + lead off the rear window and see if you get 12v there. If not, move back to the next plug (iirc theres one behind the drivers C pillar). Get voltage there? If so, you know there is a broken wire between these 2 points. Take this principal all the way back to the switch until you find your voltage.
If there is voltage at the plug onto the window, you then need to check the other side for a good clean earth.

[Tom]

Checked everything today and it was okay, so last time i tested it i done something wrong. So i fed the wire loom back into the boot and soldered the wire to the heated screen wire and it should be working now!