Speedometer?

[wjjb]

My speedometer on my 97 cc lb 5spd will work if i go over 27mph if i go under that it will start bouncing and going crazy. could it be by chance that sensor in the rear end?

[1Dieselman]

It could be but that is a odd problem. Usually if the speedometer was going to act funky it would do it at all speeds. Sure wouldn't hurt to pull the vss and see if it needs cleaned.

[wjjb]

k i will take it out tonight and give it a good cleaning, thanks for the help.

[superduty4x4]

Could be the sensor, but not likely. It could be the tone ring in the rear end... if you haven't changed the fluid in a while, I'd start there. Or, it could be the PSOM, which is a computer module built into the speedometer head. If it's the PSOM, you have to replace it. While that's not a big deal... the PSOM stores the truck's mileage, so whatever mileage the donor rig had will now show on your truck. I do believe there is a place that rebuilds them, but when the PSOM crapped out on me in my old 95 gasser it was cheaper to buy a new cluster. And... I got lucky and found one that was within a few hundred miles of actual for the truck.
Another thing to note... if you end up buying a used cluster for the PSOM, if it's not from the same year truck you'll have to disassemble the cluster and swap the good speedometer/PSOM into your cluster. There are minor differences in wiring (IIRC for a PSD 94-95 are the same and 96-97 are the same) and if you drop in a cluster from a different year truck, you'll end up with random lights on all the time and some that don't work.

[wjjb]

alright, i tried cleaning it good but that did not help, im gonna try and change the gear lube today, if not i will try a sensor since they are only $25. if thats not it then its gotta be wiring or the cluster. thanks for all the replys.

[superduty4x4]

I'd get the sensor from the dealer, it'll save you some headaches.