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Ignition Wiring Issues

imported_GarretLogan May 10, 2005

  1. If anyone is able to help, I appreciate it in advance. I have a 1998 Audi A4 1.8TQ Sport. About two months ago my head lights, horn, climate control fan (display is still active) and windshield wipers all went out. I did some research and found out that it is a common problem for the electrical ignition switch to go out. I replaced the part and everything was fine for about two days.

    This photograph was taken after the second switch was replaced. Pointed out by the arrow the wire had shorted its self out and melted the plastic from around it. With my chief A&P at work, we replaced the entire wire including the connector and yet again a new switch. Once again everything seemed to working properly, however again last night my lights, horn, etc went out again. They went out for only a few seconds earlier, but came right back on after restarting the vehicle. This morning they are all completely dead. Does anyone know what could be wrong with it? Or does anyone have a complete wiring diagram for the ignition column? Thanks,

    Garret Curtis
  2. Hi Garret,

    Sounds like maybe you have a fault on one of the components in that circuit which is leading to the whole system shutting down. It could also be the reason that the wire you pictured is overheating (due to drawing too much current via a faulty part) hence the need to replace it. If that is the case then replacing the switch with a new item will solve the problem temporarily, because a new one will be more robust than a used one, but after a short while, if there IS a fault then it will break down the new part until IT or something else fails...

    It is also a possibility that the robustness of the new items has been too much for the part that is faulty and it has completely failed now, causing a permanent fault and loss of the systems you mentioned.

    Do (all) your lights work? Does your horn still sound? Do the wipers work? Is the Climate fan running?

    Test each of the items on that circuit individually (the easiest way is to simply disconnect them one by one and then switch everything back on until it works), find the faulty item and you will have cured the whole thing...

    Those are just suggestions and I could be completely shooting in the dark there but I hope it helps...


  3. AndyMac

    AndyMac Moderator Moderator

    Yep, as Tim says try to isolate which component is causing the problem (lights, horn, climate control fan, windshield wipers). Could be a short somewhere so not necessarily a faulty component.
    Also presumably the ignition on circuit switches on a relay to feed all the above instruments (it doesn't feed them directly through the ignition switch), so my first action would be check the relays which are behind the fusebox (if you drop the trim under the stering wheel you'll have better access). You should be able to feel which relay is triggered when the ignition is turned on or I'm sure someone on here can tell you which one controls those items.

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