Odometer not working

[Greg_S]

Chaps, I havent managed to get on the forum as often as id like atm. Drop me a PM with your address etc and will send you payment details over and can get in post to you this week.

[andy j]

Pm sent.

[AndyP]

What else could cause the odometer to not work?

Mine wasn't working ( speedo was ) so I got a new gear from Greg and stripped the clocks, only to find the gear was fine. But I damaged the speedo when removing the needle, so I've fitted another set of clocks, only to find I have the same problem

[Rusty]

Signal comes from the ecu I think.

My speedo wasn't working the other day but a tap of the clocks sorted it... try that

[AndyP]

Mines the other way round, the speedo works fine it's the odometer that doesn't work. Oh and I've tried tapping it!!

[Rusty]

Must be a wiring issue somewhere...

[UrS4boy]

G22 Vehicle Speed Sensor (VSS) and G21 Speedometer info

Signal comes from the ecu I think.

You must have missed the hyperlink that I put in Post 4 on page 1 of this thread. Here it is again, in naked form:

G22 Vehicle Speed Sensor (VSS) and G21 Speedometer info
http://forums.quattroworld.com/s4s6/msgs/168463.phtml

The G22 speed sensor signal gets to the G21 speedometer without processing by the ECU. The ECU gets the signal on Pin T55/50 but only via the G21.

AAN ECU (for example, ABY and ADU effectively the same) Pin-out:
http://forums.quattroworld.com/s4s6/msgs/21009.phtml

[Error404]

The sensor is irrelevant. Andy said the speedometer works fine - the signal is reaching the instrument cluster.
Andy did you change the instrument cluster wholesale or just the speedometer?
If you remove the speedometer from the instrument board it is connected by the 4 or so long pins. I wonder if you have some corrosion or similar on yours?
I had some odd behaviour from my trip computer, which was caused by those long pins. They looked fine visually but after I dosed them with deoxit and some dielectric grease problem solved. Also check the board itself for cracks and dry solder joints.

[Error404]

Worth noting too that the later speedometers (post 94 ish) look nothing like the early ones in the PDF guide on the first page of this thread. They are far more tamper resistant and can't be dismantled without at least some desoldering of the boards. I'm not sure if the odometer gear is the same or not.

[mcandmar]

Just replaced the gear on my own odometer with one sourced from the ebay seller listed above, works perfectly

http://www.ebay.co.uk/itm/271688757359

He also sells the larger gear but on mine it was only the little gear that had failed.

http://www.ebay.co.uk/itm/271688816905

As Error has shown above the later units were a completely different design, pics below are from my own car with a 1993 date, and the later one is marked 1995. Obvious external difference is the two screws holding the dial face on are flat head screws in the 93, and torx in the 95. Looking at the later unit i can't see it failing the same way, but with the early units the key is never to reset the trip meter while moving.

[3db]

Other than broken gear, there may be cold or broken solder joints on the odometer motor or elsewhere. Try resoldering any solder joints, that look broken or unusual.

The later model VDO speedometer design is without planetary gear system. They are a lot more tamper proof and they don't seem to break down. The speedo needle is not removable. If you try to remove it, it comes out with it's internal axle and bricks the speedo completely. Bad solder joints can be a problem on later design too, but it's all repairable easy.

[mcandmar]

Electric bit is fine, the early version looks much more straight forward and easy to troubleshoot. I don't get on with this new fangled surface mount stuff

[3db]

SMD is built by robots = smaller, faster, consistent, cheaper.

[Nuvo]

Are the early and later odometers interchangeable?

[mcandmar]

Yes. If you want to fit a later speedo into your existing instrument cluster you need to use the white mounting panel for that speedo as its a different shape. Everything else is the same as i took the fuel, temp, and rev counter from the later cluster and fitted them into mine.