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A4 Brake Warning Light

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by fleecyphil, Mar 14, 2012.

  1. fleecyphil
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    fleecyphil New Member

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    Hi Guys

    Can anbody help with wiring diagram & relay details to cure this problem.
    Light comes on after cranking engine,scanned for faults & non showing,have contacted Dealer they say needs relay fitting to cicuit.
    Any help would be much appeciated.

    Regards Phil
    #1
  2. NHN
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    NHN Modmetractor Site Sponsor

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    Scanned for faults with what?
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  3. fleecyphil
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    fleecyphil New Member

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    Scanned with VCDS & SNAPPY
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  4. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    battery on its way out can cause this
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  5. alpesh26
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    alpesh26 Member

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    As above.

    Mine did the same, no faults being thrown (checked with VAS). Changed the battery and its been fine since.
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  6. fleecyphil
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    fleecyphil New Member

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    Will test battery just to be sure,but seems to crank over well.
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  7. murran
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    murran Active Member

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    #7
  8. NHN
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    NHN Modmetractor Site Sponsor

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    Does the reservoir have the 2 prongs inside like the coolant version?

    If so, scratch the surface of the 2 prongs, these fixes the coolant level sender.
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  9. murran
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    murran Active Member

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    i dont think they do. you can pull the sensor out. but its just a black oblong bit of plastic that slides in from the side, theres a two pin plug to the cars loom.
    theres a little float and some mechanism inside the reservoir, never bothered chopping a reservoir up to find out how it works tho.

    all i know is ive fitted reservoirs, 8 or 9 in the past 2/3 years.........
    im guessing theres a bit of dirt/water in the sensor mech/float thats succeptable to cold for some reason that combinded with the drop in voltage on start up causes it to flash up.
    its not just diesels either, fitted one on a fwd red 1.8t, thats the most recent one a couple of weeks ago.
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  10. NHN
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    NHN Modmetractor Site Sponsor

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    Ah you see everydays a school day :)
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  11. janzbro
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    janzbro New Member

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    mine had this fault when we bought it - the garage replaced it with one from another A4 they had in but it was still happeing so they had to take it into Audi and have a brand new unit fitted - touch wood its been fault free since.
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  12. fleecyphil
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    fleecyphil New Member

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    Thanks for all the replies,will try this during the week and hope cures problem.
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