Technical Speedometer not working

[Ultimatum Demon]

My speedometer, odometer and service doesn't roll.

Is there a common problem?

 

[Noddy]

Sounds like the speed sensor on the gearbox. Has a blue cable running at the back of the gearbox to under the box with the 2 screws on it. If not then clockset or wiring.

 

[blu73]

mk1's have the little plastic worm drive thing that drives the speed sensor do they not, sorry been a long time since i had a chance to mess with a mk1 lol. But in the gearbox under the speed sensor there is (iirc) a plastic worm drive thing and they commonly break so the speed sensor can be working and just not being turned. But if you take the speed sensor out and then with the ignition on spin the sensor, if the speedo reacts the sensor is most likely totally fine and the worm drive needs replacing - if it doesnt react then the opposite is likely true.

Keep us updated

 

[GrandePunto PL]

Some of them were 100% mechanical (no "sensors"), speedometer linkage.
https://www.google.com/search?tbm=isch&q=fiat+punto+speedometer+linkage

 

[blu73]

electronic or cable will both have the plastic worm drive thing i'm on about though

you can test same way i said before if its cable though, take the cable off and turn it by hand and the speedo should move. If it does then the worm drive isnt turning the cable, if it doesnt then its either detached from the rear of the clocks or the clocks are not working.


This thing, my money is on it, I've changed so many of them over the years and they are only getting older and more brittle as time goes by, they snap on the recess for the o-ring.

 

[Ultimatum Demon]

Thanks for help, guys. I found out my old sensor's top broke off. I went out and bought a new one. Works fine now!

 

[Ultimatum Demon]

New and old

 

[blu73]

Yup, thats exactly where every one i have seen breaks goes as well, on that line.

Did the new one not come with a little o-ring in the groove? It should have one, gearbox oil can get past it without the o-ring in there, not likely to leak much if at all but it is meant to be sealed with an o-ring.

 

[electricFuzz]

I have the same issue with a 99 fiat punto. The speedometer cable turns, it makes terrible noises (and I've seen it turning) however it doesn't stay in place into the bell-shaped plastic behind the counter. The length is good, I can pull the cable with a small plier, and it had worked a little bit when installed.

 

[electricFuzz]

I'm still troubled by the non-fonctioning speedometer. If anyone knows the proper process to fix it. I'm thinking about adding some grease. What is the purpose of the two rubber O-ring ?

 

[electricFuzz]

After investigations it turns out the parts don't seem to be the correct ones. When the gearbox starts to rotate, it brings the plastic gear down shortening the cable length and making it go out of the instrument.