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no speedo.....the problems continues and gets deeper......

Discussion in 'A3/S3 Forum (8L Chassis)' started by VAGMAN1, Feb 10, 2007.

  1. VAGMAN1
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    VAGMAN1 Member

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    [Feb 10, 2007]
    just to recap - about 3 weeks ago, suddenly the speedo and trip counters stopped working, plus fuel gauge became erratic. In summary, 2 tests done on the dash > dash pod is 100%, and diagnostic said speed sender.

    just replaced the speed sender unit this morning > no joy. ok, so you may think it's wiring, but here's the bit that's really stumped me.....

    the speed sender bolts onto a plastic 'driver' shaft which has a bevel gear on the end - this driver shaft screws into the gear box and is driven by the final drive. this in turn the end of the driver shaft connects to a rod on the sender and hence the speed and distance is calculated. removed the driver shaft to check that out - all fine,no wear and spins freely. However, with the car jacked up and wheels turning (with/without engine driving them) the end of the driver shaft is not turning, hence nothing is turning the rod in the sender etc etc.

    without the driver shaft inserted, if you insert screw driver and turn the wheels by hand, you can feel a gear moving inside the gearbox.......

    I don't get it - HELP!
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  3. simch
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    simch Active Member

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    [Feb 10, 2007]
    Sounds like the driver shaft is broken then? Does it look all ok?
    Maybe the splines are not seated right ...? Or the movement you feel trhough the screwdriver is not proper roateional movement..?

    That's weird allright, but hopefully something simple. Get the parts dept to show you an Etka sketch of everyhting inside the box in that area, it may just give you a clue as to what is broken. Proabbly some silly bit of placcy that is 50p and yet takes 6 hours to fit, knowing Audi!
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  4. VAGMAN1
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    VAGMAN1 Member

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    [Feb 10, 2007]
    definitely gearbox problem - took the speed sender out again plus driver shaft, and connected a drill to the driver end - speedo registers.

    nice.........another big can of worms.........
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  5. simch
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    simch Active Member

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    [Feb 10, 2007]
    You could just buy a GPS, then next year your car will suddenly be a "low miler!" lol

    hope you can get it sorted, its probably something real simple once the box is out and apart!
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  6. HTC
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    HTC Active Member

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    [Feb 11, 2007]
    Is the shaft locating correctly in the box?
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  7. VAGMAN1
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    VAGMAN1 Member

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    [Feb 11, 2007]
    shaft is driven by a gear connected to the diff. only way forward seems to be to remove the box then split it in 2 to get at the diff.
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  8. ash_s3
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    ash_s3 Active Member

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    [Mar 3, 2007]
    mate, ive just had this EXACT problem!
    suddenly speedo stopped working, fuel gauge showed more in it than before, odometer stopped working but temp and rev counter fine

    Turns out it was the reverse light fuse (number 7 - 10A)
    replaced this and it all works fine again, check this before you strip your gearbox down!! lol

    Think the rear washer pipe has leaked onto the rear light and just blown the fuse

    Hope this helps pal

    Ash
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  9. VAGMAN1
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    VAGMAN1 Member

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    [Mar 4, 2007]
    thanks ash - but it was the gear box! car is all fixed now - turns out the plastic gear that drives the speedo sender has actually been mashed down to nothing!

    how on earth could a fuse for the reverse light have caused your problem though???!! and how did you track it down?
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