Erratic speedo

[Mat 71]

I have an 83 S auto...pretty sure it is an aftermarket guage package installed by PO...it lights up blue.

I can take pictures if needed.

The speedo works fine sometimes, 'dances' around other times, and just plain old doesn't work other times. Doesn't appear to be any rhyme or reason for it.

I'm starting to get annoyed at this point, as not only do I have to do the math when it works (miles to km's), now I have to guess the speed via the rpm's.

Any thoughts?

Thanks in advance.

M.

[rhjames]

blue lighting is probably just a light bulb change (I changed mine to red)

speedo "dancing" could be anything from bad connections to bad sending units to "who knows"......

it's really tough to diagnose something like this without being there-----

[Normy]

My advice is to pull the pod, gently remove the gauge cluster, and clean the contacts with a pencil eraser. It's probably just something simple like that. The speedometer is an electronic device on these cars- no cable. It's really just a "Hall effect" impulse counter. A magnet is attached to the rear differenctial, and a pickup is attached to the differential housing. There is a wire that runs forward to the speedometer itself, and the device counts impulses. Via a chip it calculates the number of impulses per second that it is receiving, and in turn submits a voltage to the needle, which works against a spring. Somewhere in there something isn't cooperating.

In my experience, the printed circuit on the back of the cluster is the culprit of a lot of gauge problems. I just replaced mine, and I'm not certain after looking at it how I never wound up with an electrical fire inside the pod...

If you don't care for your blue lighting, then change the colored bulbs. You might have a Speedhut EL-glow gauge package installed by the cars' PO however. This can be easily removed, but you have to remove all your needles to get the EL-glow plates off your gauge faces, and the needles are very easy to break.

Good luck-

[jsbc]

try cleaning the connection on the rear of the gearbox it gets crappy and then wont send to the guage ,mine would not read until 40 mph then worked fine until it dropped off at below 20mph

[Mat 71]

Thanks guys!

We have a long weekend coming up this weekend (Canadian Thanksgiving). Hopefully I will find some time to try the suggestions.

I'll let you know how I make out.

Thanks.

M.