Technical Fiat Brava 1999 1.2 - Weird speedo issue

[Kaidus]

Hi all,

Weird issue with my Fiat Brava.

Basically, when I'm driving, car drives as normal but I'll glance down at the speedo only to notice that the speedo has failed (needle down at 0 even on the motorway) and the mileage counter is flickering in and out (and not counting any miles). Car is driving as normal and rev counter/temp/fuel gauges are working. Lights are also working.

The even weirder part is that the next time I turn off the ignition, wait for a count of 5 and then restart the car - it all starts working again!

Any idea why this is happening and how I can fix it?

 

[varesecrazy]

Hi, and welcome

poor connection / earth would be obvious answer, how many miles on it..??

my old 1.1 punto did this.. apparently it was common..!!

charlie

 

[Kaidus]

78000 on the clock.

Easy to fix?

Just thought - I reset the ECU recently and it is only since then that this has happened...could it be that I haven't put the battery connection back on?

 

[varesecrazy]

could be coincidence.. may be worth checking the "extra" leads on battery clamps,

Neverth will know if it's a board / component issue..,

charlie- Oxford

 

[Neverth]

Its a fiat, give it a good open palm slam on top of the dash (turn lights off so you dont burn the backlights).

Second step would be connecting free version of fiat/multiecuscan and see if the gearbox signal is good.
If ECU wont see signal (ecu has own milage counter) I would go on cleaning the contacts for the gearbox sensor.
If ECU has signal, the connector block behind the clocks would be next suspect (also this connector if the slap helps).

Flickering display sounds like power issue (possible its the connector, voltage out of spec so the micro driving the display browns out and contrast voltage is off.), but I would check the above first.

If it still wont work, my guess is the voltage regulator (12v->5v/3.3v) for the micro, pretty easy to repair if thats the issue.
Another possibility is short on board and the voltage regulator is heating up and going into thermal protection mode.

These are just guesses based on very little information.

 

[Kaidus]

Cheers, will try these tomorrow if possible.