Technical The Usual Speedo Problems - MK1 Punto

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Technical The Usual Speedo Problems - MK1 Punto

spf

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Hi everyone, first post, and guess what, some issues!

Have recently bought a '99 60sx and the speedo has started to play up.

Have had a trawl through the forums and it seems that this is a fairly common set of problems - the speedo sits at 20, and sometimes goes to 120 and above with the mileage ticking over too. when you turn off the ignition the needle goes to zero as normal. there's quite a few old threads but they generally seem to peter out before any conclusion, so my apologies for raking this up again!

Have taken off the instrument panel and it looks ok, no obvious cracks or faults with the circuit board, and all the connections seem to be tight - only thing here is that the copper is a little dirty on the pcb where the connectors slide on and off - am i right in thinking this only shows that there is a good tight connection here, or should i give these a rub with a little contact cleaner?

All fuses look good, no probs at all, they seem very clean (worryingly so possibly!)

Once I had looked at the instruments and panel i took off the speedo sensor and worm gear - they also seem fine - the sensor seems dry and no obvious loose connections - I actually get the impression it may have been changed before due to a different colour sheathing on the cables.

The little plastic worm gear looks to be in decent order too - no major wear or damage at all. would i be able to visually tell if it was screwed though?

anyway, put it all back together and then the speedo needle now wasn't working - mileage was ticking over fine, but nothing from the needle. This is leading me to believe that it's actually a fault somewhere in the speedo unit itself - there must be decent signal to it for the mileage to tick over correctly is my reasoning - can anyone confirm that? (or shoot me down in flames:) )

So, in summary, if anyone can pick through my reasoning i'd appreciate it, my plan for next course of action is to buy a 2nd hand panel and see if that fixes the probs - is this my best way to go? if i can find a breaker locally (dubln) who'd let me do it, would the best thing be to drive over and try the panel / and or speedo sensor?

thanks in advance for any advice!
spf
 
Must be a new Fiat virus.

Exactly the same happened to ours 3 days ago.
As you say, wild flickering from 20mph to off the scale and then back to normal as if nothing had happened

Currently have head in sand hoping the problem goes away!
 
yup - it definitely seems to be fairly common.

anyway - brief update - got a new instrument panel this morning and it's still doing all the same stuff - except the speedo needle is very very rarely moving now. Looks like my reasoning about it being the panel due to the miles still ticking over is nonsense :)

Am going up to a local breakers this afternoon to replace the speedo sensor unit (and gear if neccessary) so will let you know how i got on.

as a slight aside - don't turn on your ignition if not all the connections are made to the instrument panel (probs best disconnect the battery actually). I now have the airbag warning light on due to trying to figure out which connector was for which sytem on the instruments. doh! ah well, should only be a tenner to get it reset.
 
Thanks spf
Would appreciate an update as and when you sort it!
Got 'til August for next MoT so no pressure!!!!
 
was the speedo sensor.

everything back to normal. I'd suggest a quick trip to the local scrappy/breaker and try a new sensor. they're dead easy to get on and off, especially if you only remove the electronic bit to try it first.

hope you get it sorted as easily as i did in the end fiat freak.

just have to decide if i like my new instrument panel better than my old one now :)
 
if you look at the back of the engine, roughly in the middle but slightly towards the passenger side, there should be a wire running to the back of the transmission - this connects to a plastic part (round top with tubular piece protruding into the engine) which has a 20mm nut connecting it to the transmission.

if you have a 1.2 8v its shown (and labeled) in the guides section - "where everything is on a 1.2fire engine" (would put the link in, but not allowed till I have 5 posts!)

You just need to undo the 20mm nut and lift off the speedo sensor. disconnect the wiring and rreverse the process with your replacement one. takes 2 mins!

only other thing that may be wrong there is that the actual speedo sensor unit connects to a plastic gear inside the transmission. to get this out, just below where you undid the 20mm speedo sensor nut is a small screw (about 8mm hex head) - loosen this off and lift out what is left in the hole where the speedo sensor was - there should be a metal sleeve and inside that a plastic gear. have a look at it and see if it's intact, especially where it connects to the speedo sensor - if it looks worn this may be your problem.

once you locate these it's really easy - I think the arrangement is basically the same on a 16v engine, but am open to correction on that.

the big question is - do you have ABS? If so, this all means nothing as the speedo works in a different way - by the sounds of your problem I'd guess not tho! seems far too similar to not be the same thing.

hope you get it sorted!
 
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Ahhhhh :bang::bang::bang::bang:

Changed speedo sensor for a brand new one
Worked fine for 20 miles and now playing up exactly the same
Sometimes I hate cars!
 
Hi fiat freak, didn't see that you'd replied again...

had the same sort of problem when i put the new sensor in - i ended up taking it off again and just making sure that the plastic worm gear was well set / positioned, and then very carefully re-assembled the electronic sensor. seems to have sorted it (haven't been 'going' at 140mph for a few weeks now nehows!)

hope you get it sorted.

seán
 
Fiat freak, if it is not your speed sensor, then chances are it is the little circuit behind the dashboard. Quick way to determine this is if the fault corrects itself when you slap the top of the dashboard hard. If this does fix it, then chances are it is not the sensor, but the circuit in the instrument panel.

You do not need a whole new instrument cluster, or even a new speedometer. All you need is the little circuit board that sits behind the speedometer. I bought a speedometer including this circuit for a about £25 brand new, delivered, from Ebay. Remove and strip down you instrument cluster, remove the circuit board, unclip from the speedometer and the main board cabels then replace with the new circuit. 15 minute job if it all goes the right way.
 
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Hi everyone! :)

im new on here so i apologise if this is posted somewhere it shouldnt be :eek:

i have a 1994 elx 90 cabrio, the speedo is not working at all and the fuel light is on constantly... the rev counter and other dash lights etc are all working as they should... just not the speedo...?? if any one can help id really appreciate it, i know my way around a car being brought up with 5 brothers and a dad who are all mechanics, unfortunately theyre all at the other end of the country! and i reckon asking an actual fiat fanatic would help me out a bit more :)

cheers in advance! Trey :slayer:
 
My problem on the mk1 punto 60 did turn out to be the speedo instrument itself as Mike salt posted. I found a replacement pod at a Scrapyard on e-bay. As the mileage was very similar I just swapped the while pods over. Cost me £20 for the pod and changeover involved 2 screws and 3 cable plugs. 5 minute job and perfect since(oh hell just tempted the fiat god)
 
Hi everyone! :)

im new on here so i apologise if this is posted somewhere it shouldnt be :eek:

i have a 1994 elx 90 cabrio, the speedo is not working at all and the fuel light is on constantly... the rev counter and other dash lights etc are all working as they should... just not the speedo...?? if any one can help id really appreciate it, i know my way around a car being brought up with 5 brothers and a dad who are all mechanics, unfortunately theyre all at the other end of the country! and i reckon asking an actual fiat fanatic would help me out a bit more :)

cheers in advance! Trey :slayer:
Trey let us know if you still have instrument panel problems, cause I have just changed the panel of mine for a different style so have a working spare going.

Cheers

I

I
 
if you look at the back of the engine, roughly in the middle but slightly towards the passenger side, there should be a wire running to the back of the transmission - this connects to a plastic part (round top with tubular piece protruding into the engine) which has a 20mm nut connecting it to the transmission.

if you have a 1.2 8v its shown (and labeled) in the guides section - "where everything is on a 1.2fire engine" (would put the link in, but not allowed till I have 5 posts!)

You just need to undo the 20mm nut and lift off the speedo sensor. disconnect the wiring and rreverse the process with your replacement one. takes 2 mins!

only other thing that may be wrong there is that the actual speedo sensor unit connects to a plastic gear inside the transmission. to get this out, just below where you undid the 20mm speedo sensor nut is a small screw (about 8mm hex head) - loosen this off and lift out what is left in the hole where the speedo sensor was - there should be a metal sleeve and inside that a plastic gear. have a look at it and see if it's intact, especially where it connects to the speedo sensor - if it looks worn this may be your problem.

once you locate these it's really easy - I think the arrangement is basically the same on a 16v engine, but am open to correction on that.

the big question is - do you have ABS? If so, this all means nothing as the speedo works in a different way - by the sounds of your problem I'd guess not tho! seems far too similar to not be the same thing.

hope you get it sorted!
sorry to bring this up again, do you know on the back of the engine what the small circuit board is for? I have a slight idea, one wire was not attached am i right in thinking this can be the reason my speedo doesn't work?
 
Just to add to this and to thank the previous posters who have saved me a lot of money! My Punto Mk1 1.2 developed the erratic speedo, sticking on 20 then zooming to 120 etc. On reversing it would wind up to 100 then on going forward lurch back to 20 with noise. Mine has no cable and is the electronic so guessed either the sensor on the gearbox or the dash end. The big clue was if I bashed the dash, it would sometimes clear the fault in the early days.
So I removed the dash, took off the cover then undid the 3 screws on the speedometer so it could come out. Between the speedometer and the main back of the unit where there is a thin electrical track matrix, there is a small PCB. Looking EXTREMELY carefully I found a tiny crack in the solder mount where one of the edge connectors goes onto the board. Soldered that back solid and the others for good measure then tightened the end of the 3 wires going onto the main back (one a screw and the other two small nuts) and re-assembled.
This has cured my problem completely. About a 30m job with no pitafalls. Hope that helps others and worth a check before buying replacement units.
 
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