Classic Audi Technical Mech/Tech Electrical problems » Rear Screen Heater 80 B3

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Old 30-09-18, 06:08 PM   #1
William Blyth
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Default Rear Screen Heater 80 B3

I've recently replaced the heater matrix on a 1991 Audi 80 b3 1.8 S, and now find that my rear screen heater only works when the dipped lights are on. The only thing I can think of is that I've found a single cable with no obvious fitting location at the back of the heating controls. Any electricians out there with any ideas?
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Old 30-09-18, 07:01 PM   #2
Mellis46
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Does that cable have a white, funny shaped plug on the end of it? If so its the connection for the 3 auxilliary gauges - it doesnt connect to anything if you haven't got those.

Everything got plugged back in properly behind the dash when you built it back up? Checked all the fuses etc?
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Old 30-09-18, 07:22 PM   #3
William Blyth
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The wire was single cable. with a single female connector. I thought I had labelled all the wires as I took them apart, so I was surprised to find an unmarked cable when reconnecting. I was hoping that it may have been an earth cable. Thankyou for your help, at least I can now disregard that cable. That at least leaves me to find another solution to the "rear heater only working with main lights on".

Last edited by William Blyth; 01-10-18 at 11:34 AM.
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Old 08-10-18, 10:38 AM   #4
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Demister switch now checked and all OK. Fuse checked - OK. Checked not connected to Fog Lamps by mistake -OK
Illumination light came on when ignition was turned on Pressed switch NOTHING Turned on dipped beam- It works

Last edited by William Blyth; 08-10-18 at 10:42 AM.
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Old 08-10-18, 10:58 AM   #5
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No matter how random, tried all the earths, bad earth under a tag and its using the dipper beam as a return path.
Seen it happen before

Just a thought
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Old 08-10-18, 12:35 PM   #6
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Disconnect the two fog lamp switches and try it again
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