This one is wierd. Normally when I put the rear window demister on it works (slowly), the light comes on, etc. However I lose signal quality on my pioneer radio. However a couple of times I have found when I start the car up the light comes on on the dash quite dimly and the radio reception is terrible. However when I turn it on the light goes brighter and the radio reception comes back to normal! EH?!!?
I expect the reason you lose signal quality on your radio when the demister is on is probably because it uses the demister as an arial. It does on my FD, and I can get a loss of quality on the radio on that. Don\'t know about why it\'s lit dimly though on start up.
Right, I\'ve got to search my memory box now. Takes me a while \'cos theres a lot in there.
Firstly, the factory radio aerial on the FB (1st Gen) is an expensive motorised up/down unit on the back O/S wing. The demister wiring runs in that general area to the O/S hatch strut, so the aerial cable runs parallel to the demister wiring.
Heres where the memory comes in. On one of our earlier FB\'s, I think it was the Mk 2, 1983, the demister switch, which is a sort of rolling small solid tube contact mechanism in the switch body, wasn\'t contacting properly and I took it apart and put a new tube contact in.I made it from a cable crimp lug I\'d got lying around. Heres the connection if you\'ll excuse the pun, A bad switch contact might be enough to still work the demister, but it will be generating electrical noise, which the aerial would very probably pick up in the wiring run at the back of the car.
Hope this helps.
I thought it might be the switch, mine is a later 85 model. So I will pull out the switch and give the contacts a clean. I\'ll also see if I can reroute the cabling.
I\'ve looked at our 1985 model and another possibility is that 1 of the push-on spade connectors on the back hatch is loose or corroded. (Demister doesn\'t go via the struts, as I said from my Shackleton\'s armchair yesterday). Same thing though, it will generate electrical noise in the vicinity of the aerial cable if one\'s loose. Easy fix.
LOl..heheheheheh.......I drove the whole winter with no demister,no heater,:Hammer :rollin :Giggle .......to be honest..."I never look back" :evillaugh
the wires have probably got hot and melted, if you are using the original ariel these cables run next to each other as David said, i would lift the drivers door foot plate and check the wires there, take the rear drivers side cover off (where the rear speakers are) check all the wires there, i had a FB with melted wires along the same path as this, the rear demister is a simply set up with no switch off apart from a 30amp fuse, someone could of left it on for quite some time and them wires get hot!
another thing to try is a seperate arial disconect your existing and if there\'s no problems with reception its got to be a short circit!
Mark