My 95 Impala digital speedo and odometer go black sometimes for days, then come back on, Impala forum.com said this coul be as simple as a cleaning issue or as expensive as a full replacement cluster,

there are different speedo gears in the transmission available that will allow for some ratio changes in the diff so check with a dealer spares to see if any are available for your vehicle
when you say smaller tire , is it a smaller diameter rim that was fitted
if that is the case by fitting a larger tire case may get back closer to the correct reading
by that I mean for example a 195 25 r14 case can be replaced by a 195 95 r14 case as the difference is in the 25 to 95 measurement
the 25 measurement makes for the rim almost touching the ground where the 95 dimension stands the rim well up off the road and because of that the distance covered in 1 revolution is far different to the distance covered in 1 revolution by the 25 size tire
that solution may put the car back too high for your back problem so if the gears replacement is not possible , then a last solution may be to find an instrument repair shop and have the gauge re- calibrated to the correct reading according to the speedo gears in the transmission
if it is auto with a VSS unit that signals the speedo there may be changes in that area that are possible

hey and oldie but goodie.
why not post the full symptoms. ????

Speedo dead, makes noise, bounces? what? stuck high? what?
odometer dead.
CEL glows running, the check engine light glows, running
and you insert the 1cent paper clip in the DLC connector and you get
code flashing. code 24, VSS dead?
http://www.fixkick.com/CEL/CEL.html

if yes, the cable has snapped. (fell off at either end)
if not VSS dead, then the speedo is dead
if both odometer and speed are dead and VSS are dead the
snapped cable, or cable fell off rear of speedo head.
if VSS is not bad. (no 24s)
and only speedo is dead but , odometer is good
then that means the actual speedo clock inside the head is bad.

to repair a dead speed/cluster, you replace the whole head
if real frisky then you do this.
suzuki even sells new clocks, but are very expensive
what i do is find a used head. and use that. (car-parts.com) or at fleabay.
sometimes i mix 3 heads to get one, good head.
that is all you can do, on old cars unless rich, and $200 head is pocket change.

http://www.fixkick.com/sensors/speedo/unsafe-at-any-speed.html


tell more get more, ask.

The digital speedo is repairable. The issue is, the contacts of the display are no longer making good contact with contacts on circuit board. A good gauge repair service should be able to rectify the issue. Good luck. Ron @ Speed-O-Repair.

Remove instrument cluster and have it tested or, if you have access to a scanner with data-stream capabilities, you could check to see if vehichle speed sensor is emitting proper voltage /signal.

Replace speed sensor in transmission, or replace instrument cluster depending on which is at fault.

sounds like the ground for the cluster is loose or corroded.

you can remove the cluster and try to clean the connector parts stores have a electrical contact cleaner that can help

Speedo cable may be loose at the gearbox or may have snapped inside, sometimes you cant see but inside the cable tears apart. only other option is the instrument panel if the cable has come loose from there then this will also cause the fault. Esy to check just unscrew the instrument panel and see if the cable is sat correctly.

If you need more specific advice please get back to me.

Regards

Dan

It sounds like the Speedo cable is going bad remove the cable connector on the side of the transmission and twist the cable and see if the odometer moves, you can also pull out the cable from this end and check the Speedo end, if it's bad it will be rounded off rather than square. If the gear in the transmission is bad you can put the cable into the end of the Speedo gear on the transmission and try turning it if it turns around say a half turn or more then the gear is bad, all you do is pull out the bolt and the small horse shoe clamp and wiggle out the gear and go buy a new one at the dealer or transmission shop, if the cable is bad you can buy a cable kit for $12.00 the gear is about $10.00. The check engine light would come on because the Speedo is malfunctioning and uses the info from the Speedo to input injector pulse width.

have the dsme problem. need to chech each of the 3 wires for continuity between the v.s.s. and the e.c.m. if good then the speedo is bad.