I replaced my vss two days ago,speedo worked for about 40 miles and then started to bounce.Any suggestions please?

 

Is it manual or auto. If it's a manual look at my resopnce to post After market Speedometer follow the suggestion re: tightening the yoke nut.

Bob

 

It's an auto 4x4.I did read your post on this issue,but when I changed the vss it worked awesome,now the more I drive it the worse it gets.I can't help but think that I did something wrong,over tightened the vss,I du know.

 

I found something strange driving from town tonight,the speedo was responding to the engine revs. Could my problem be a ground?

 

That is possible, but I'm not sure if your problem and mine are the same. When I first start mine and begin driving it pegs out at 100 mph, then as time goes along, may 10 minutes, it starts reading normally. So I'm not really sure what would cause that. I do know that I had to bypass the engine computer to get OD for my auto. I also had to go through 4 voltage regulators to get one that still acts funny. It will charge normally, then once the battery is charged the needle will run up high then bounce back down and continue doing that. Also while the lights are on they flicker brighter and dimmer along with the bouncing of the needle. I shot some video of the needle behaviour. I'll post it to youtube and post a link in here ASAP.

 

That video is cool ,but the problem sucks though,your voltmeter looks like my speedo. I'm sure eventually somebody will set us straight on this awesome site.

 

I know this is an old post but I was wondering if anyone ever figured out what was wrong with their trucks. I have a 91.5 that my voltmeter, speedo, and water temp all bounce that way.

 

I did. It was a poor connection at the vss. Brand new and a bad connection imagine that and I changed both ends.
Your issue sounds different to mine. Just my speedo was jumping.