Sort of an accessories question.. Demisters for rear

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stu113
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Joined: 03 Oct 2012 08:50 pm

Sort of an accessories question.. Demisters for rear

Post by stu113 » 04 Oct 2012 11:37 pm

Recently bought a 340 and it was stripped by the original owner. They even took the wiring for the rear demister out. I have the switch but nothing to connect to.. Any one have any ideas? How do they get heat? Could i just run a ground and a live? :/ not 100% clued up on electrics just yet..
Cheers

Nimminz
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Location: Durham City, NE England, UK
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Re: Sort of an accessories question.. Demisters for rear

Post by Nimminz » 04 Oct 2012 11:43 pm

pretty sure it goes...

Ignition live -> Fuse -> switch -> Demister -> earth

Hope that helps
'88 360 +T LSD - sold
'87 760 TDI (D24TIC) - sold
'04 V40 D sport (F9Q, decat, Remapped, launch control)
'89 740 SE (b230ft, 12psi, V-cam, headwork, 'remapped', banded steels)
'86 340 DL 1.4

stu113
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Joined: 03 Oct 2012 08:50 pm

Re: Sort of an accessories question.. Demisters for rear

Post by stu113 » 04 Oct 2012 11:49 pm

So if i wire a live fro the cig lighter to the switch to demister then ground it should work? Cheers

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Speedy88
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Location: Bristol

Re: Sort of an accessories question.. Demisters for rear

Post by Speedy88 » 05 Oct 2012 07:51 pm

You could... but its neater to do it directly from the battery.
'88 340 Williams (Sold)
'85 360 GLS - Drift project (Sold)
'77 Colt Sigma
'96 940 Drift project

Ride_on
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Location: Belfast, N. Ireland

Re: Sort of an accessories question.. Demisters for rear

Post by Ride_on » 05 Oct 2012 10:22 pm

That would not be good, you could leave the switch on and drain the battery. It should come from the relayed ingition-on-12V via a fuse. Manual shows fuse Z18, current track 32, but I doubt that is any help.

There should be a black+brown wire going to the indicator light in the dash (not the switch lighting shown in the phot). That connects to the switch and the demister. the other side of the switch then goes to Z18 via a white+green wire, but this maybe the one that missing (or both). Look at the photo, you might be able to trace where it has been cut off.

Interestingly my wiring block is also overheated, quite alot of current going through this switch, I remember replacing a few in my time. It would be better with a relay to reduce the load on the switch, nevermind a time switch to turn it off after 5 mins or so.

Heated seat switches and electric windows switches also go due to arcing I think, not a good electrical implementation.
Attachments
IMG_3135s.JPG
Rear demister wiring
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

stu113
Posts: 8
Joined: 03 Oct 2012 08:50 pm

Re: Sort of an accessories question.. Demisters for rear

Post by stu113 » 07 Oct 2012 05:23 pm

That seems a long and complicated task.. Any temporary method? One that takes a few mins to wire up then when have more time on my hands re think the situation. Such as the idea i posted? But would that overload the switch? As i would turn it off after the window is done and would be a few weeks solution..

Ride_on
Posts: 2262
Joined: 26 May 2009 05:34 pm
Location: Belfast, N. Ireland

Re: Sort of an accessories question.. Demisters for rear

Post by Ride_on » 08 Oct 2012 10:12 pm

Yes of course, find the wire ends that have been cut-off and rewire them to the switch, this will make it 'original' and work fine as you suggest. Make sure you use the correct current rated wire.
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

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