There is a small gear in the back of the odometer that breaks when the trip
odometer is reset while the car is moving and usually when the last two digits
are '99' on the main odometer.
Some owners who post of Audiworld have reported varying success in pulling the
instrument cluster and disassembling to get to the part. They then use glue to
fix it. Others find a working IC in a used parts (junkyard) place for $20 to $40
and replace the whole thing. Others just live with the inconvenience because
finding a working IC is rare because almost all T44s have encountered this
former four T44s '84 - '91
current 98.5 A4 1.8TQM
Seems to be a very common problem. There is a little gear wheel in
their, which is placed between a small stepper motor and the odo
wheels themselves. It feels quite rubbery, don't know whether that's
the age or whether it's like this from the beginning. If the
speedometer is working but the odometer not, that's a very likely
I replaced it with one from the scrap yard, only to get the same
failure a year later. It's a bit of a pain to take it out, so I would
recommend getting a new one. It looses one or two of its teeth, I
don't know how one would be able to fix that with glue (and it would
very likely loose more teeth later anyway).
I don't agree with the statement that it happens when the trip
odometer is reset. First of all it dis-engages the mechanism, so it
shouldn't be a problem. Nevertheless, I am sure I didn't reset the
trip odometer while driving and the second failure was witth the trip
odometer at ~360km (can't remember where it was on the first failure).
Scott Brotherton from Continental Imports (
http://www.continentalimports.com ) used to sell the gear for US$ 20
plus shipping. If anyone knows a European source, I would appreciate
it (shipping from the US is just very expensive).
If you decide to take it apart, you will need to get the needle off.
The best way is to twist it carefully counterclockwise, then it will
come off (don't try the pulling straight off some recommend). I got
this trick from Rick Borth from Overseas Speedometer (
www.speedometer.com ). If you decide not to repair it yourself, it
might be worth to get a quote from him.
There is a web page somewhere with the wiring diagram of the
speedometer. It's actually quite simple. If you can't find the web
page, I might still have a copy of it on my pc. At some stage, I made
some sound files with square waves, corresponding to different speeds
(20, 40, 60, ... km/h), hooked the speedometer up to the pc sound
output and played the sound files. That way I was able to test the
speedometer and odometer and to callibrate it at the same time. I
might still have them somewhere, let me know if you need them.
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