* Speedometer Help!!! *

I recently got this car from my mom who does not need it anymore, and the speedometer was not working when I got it. So when I first got it I took it to a local repair shop to have the speedometer checked out. They said the computer was reading the speed correctly and the problem was probably in the speedometer cluster.

So I got on ebay and found one and bought it. I got it about 2 weeks ago and installed it myself. No problem with the install but the speedometer did not work. All warning lights and the gas gauge worked but the speedometer never moved off 0 MPH. So I called the guy I bought it off of and he said for me to send it back and he would have it repaired.

So I sent it back and I got it back today. Installation went smooth like before, but once again all lights and gas gauge work but no speedometer. I called the guy again, and he tells me he had Autocraft Electronics test the speedometer, and it checked out fine.

So what is the problem? When you turn the ignition on both the old and new speedometer needles raise to the 0 MPH position but they never move. All lights and the fuel gauge work on both but the MPH needle never moves.

Sorry this is so long but I really need some help here, all is appreciated!

Does the odometer work? When the speedometer went bad in my 97, the odometer still worked fine. The speedometer would jump around though. Because the odometer worked, I kind of ruled out the vehicle speed sensor. If both the odometer and speedometer don't work, it is probably the speed sensor.

No the odeometer does not work. Where is the speed sensor located and is it costly? Thanks!

I'm not sure how much they run, probably about $40. I think the vss is below the fire wall, passenger side, kind of hard to get to.

If the computer is showing the correct speed but the speedo is not, what could the problem be?

Maybe it is loosing the signal between the computer and the speedometer cluster due to a bad wire or connection (if you are absolutely sure the vss is working). That cicuit may not be complete. What I would do is get a hold of the detailed wiring diagrams (public library has all the books-can photo copy them) and figure out which wire carries the speed signal from the computer to the dash. They are color coded and the diagrams id the color. Could also check the signal from the VSS to the computer. When I check stuff like this, I usually run a straight pin into the wire and then attach to it with a digital voltmeter to get a reading. Since you have to check it when you are moving, you can duct tape the voltmeter to the winshield, so that you can read it from inside the car. I don't know what range the vss is supposed to send though. It is probably a measure of resistance--not sure, the book may say. At least you may be able to determine if the signal is getting to the dash pin. Could even be a bad connection at one of the computer wiring harness hook-ups. Need to figure out exactly which wire carries the signal to the gauge cluster. Also, look the connecter pins over real good.

The computer may buffer the vss signal to some degree. My experience has been though, that the wiring is usually okay. If there are problems with it, it is either a bad ground wire connection or a bad connection where the wire connects to the pin, if at all. More likely though, it is the sensor or some problem with the gauge cluster. I have to 97 Lesabres and have replaced the gauge clusters in both. One of the clusters I got at a salvage yard was also bad. Had to take it back and get another. Each time the speedometer went bad (in my case) the odometer still worked.

Per my book references, the VSS had 2 wires. Should be one yellow and one purple. The vss generates ac voltage that is proportional to the vehicle speed and goes to the computer. The signal from the computer goes to a solid state unit on the instrument panel which drives the pointer of the speedometer. The wire from the computer to the cluster is a dark green/white wire. It connects to terminal #13 on the computer.

Thank you! Keep the ideas coming, I'll try to get this stuff checked out!

Thank you! Keep the ideas coming, I'll try to get this stuff checked out!

These clusters with age can start acting crazy.
I replaced my old instrument cluster with a used one of a 95 park avenue and it works great!
The buick dealership said it wont work, and wanted to charge me full price for a brand new one. My old cluster kept all the warning light on, during driving operation. But the speedometer and everything else worked. They isolated the problem to the Cluster ONLY. Not the computer.

The 93 Lesabre Limited and the 95 Park Avenue both are interchangeable clusters!@!


In your case it may very well be a speed sensor. Does the ABS light come on? Those use the same speed sensor i believe. I have also heard that the veheicle speed sensor is also in the transmission.

No ABS light and the transmission shift/operates fine. Took my car to a local shop and the guy there said the computer is reading the speed fine? So I guess that rules out the VSS. So it is either the wiring from the computer to the cluster or the cluster is bad?

If I were working on it, I guess I would want to see the voltage fluctuate in direct correlation to the vehicle speed before entirely ruling out the vss. Did the computer just not have any codes stored related to the vss, or how did the shop determine the computer was reading the vss signal accurately? Did they hook something on it and drive it and examine the voltage from the speed sensor changing as speed increased, etc.? If it is okay, then it must be the cluster because the needle jumps up to zero, but goes nowhere from there. Somehow, a pulse or power is getting through initially to jump the needle up to 0 mph.