Non-Operational Speedo on a restored Alfa 90

[Rocco166]

Hi All,

I am in the process of returning my Alfa 90 to the road after a few years of rest, over the past 4 months my mechanic has gotten the car 99% ready for re-licensing the only outstanding issue is the speedo which has an intermittent fault.  The original speedo would read from 0-45kp/h then revert to 0 kp/h until it reached 70 kp/h + where it would read normally again - the pick up sensor was replaced but that did not resolve the problem so the entire instrument panel was sent to Melbourne to be refurbished. Once the speedo returned it worked fine for 10 minutes when the car was started from cold and then reverted to 0 kp/h and refused to work again - neither the digital readout for kp/h or the "sliding scale" LED kp/h display work - every other instrument is working fine.  ASV dismantlers in Sydney supplied 3 different second hand instrument clusters and 2 of them have intially worked but then the speedo has "dropped off" and gone back to a 0 kp/h reading. 

Has anyone had this problem with their Alfa 90 digital dash? Short of re-wiring the entire speedo, which may or may not solve the problem, my mechanic and I are at a loss to figure out what the issue could be.

The car can't be relicensed without a functioning speedo and as this is the final part of the restoration - the failure of the speedo is a frustrating problem.

Any ideas would be gratefully recieved - I just want to (legally) drive my 90 again 

[dehne]

i have never had a prob with my cluster b4 and ive owned a few 90's one thing i would say to sheck is the earth wire on the sender unit its located under the rear seat and make sure all the connections behind the cluster are ok. if you need any other parts for ur 90 let me know as i have heaps of them

[MD]

Rocco. How original does the car have to be ?

[Rocco166]

thanks Dehne and MD,

I'll pass the info on to my mechanic - he's as frustrated as I am with this fault - who would have thought and 80's Alfa could be so tempramental

MD I did float the idea of changing to a "normal" analogue dash but that idea was shot down - what are my options for the 90?

[MD]

Rocco,

With all due respect to even the best mechanics out there, this type of instrument and its operation is really a job for an electronics technician. The two trades are worlds apart. Therein lies some of your problem. I could write a book on the dramas I have gone through to get electronic circuitry dope out of
the Italians to make various combinations of speedo heads work with different generation senders and the like but all they ever do is give you the cold shoulder and hold their so called intelligence very close to their chests.
So it's impossible to say what the problem is which can range from faultly micro chips, cracked circuit boards, dry joints on the boards, changed values of components, dried out electrolytic condensers for the speedo itself. You could have a similar story with the sender uints. And finally there may be spurious signal interference in your line voltage that either inteferes with the normal circuitry function or actually damages it when in use and once done, its cactus.
I recently had no end of trouble with a 75 speedo head. It was intermittent. However it was only intermittent when the tacho was in use. If the tacho was disconnected, the speedo worked fine -most of the time but not continuously. In my case, I wound up installing a complete replacement binnacle set. It now works fine.

If you didn't want to remain genuine, you could always run a speedo off the front wheel and use an off the shelf speedo head that matches the sender.......

[Mat Francis]

Rocco,


If you didn't want to remain genuine, you could always run a speedo off the front wheel and use an off the shelf speedo head that matches the sender.......

Works a treat in my alfetta!

[Rocco166]

thanks to everyone for the suggestions for fixing my electronic speedo on the 90 - after much investigation and deconstruction of the dash I found a short in the loom against the firewall that was intermittantly shutting down the feed to the speedo - the loom has been repaired and the speedo is working fine.
Now I just need to get it over the pits and re-licensed.....

[MD]

Ah the old knackered loom trick...geez  !!

[alfagtv152]

Hi Guys,
Just for interest I was shown a range of speedo's the other night which are basically a GPS Velocity readout but look like speedo's!.gotta love that.Just has power input and an antenna to pick up the satelites.
Cheers
Andrew

[MD]

Interesting indeed !!
Wonder how good it would be in the concrete jungle?

Only drawback I can see is the inability to wrap the pointer around the end stopper.