I posted this before that my speedo needle jumps around at higher speeds. Someone suggested it was the VSS. Then my ABS light was coming on too. I changes the VSS, no ABS light but the speedo needle stills jumps around at higher speeds. What else can be making the speedo jump around. Can't use my cruise because when the speedo jumps it cancels my cruise. It's frustrating!! I did cnage the rear end oil and inspected the tone ring, it all looks good. The wiring to the VSS is good and I followed it to the frame and it isn't rubbed through in any places.

 

I was gonna say the ring probably has something on it, but you said you checked it.

It could just be a bad connection behind the cluster.

pull the cluster and use a pencil eraser to clean the contacts.

You can do it with a scotch brite pad, but its very delicate, you might take off metal. You just wanna shine em up, so use the eraser.

 

Why would it only jump around at speeds above 50 mph? It's weird, I might need to talk to a local gear shop in town and maybe I missed something on the ring. What else could it be? I am not thinking it's a bad connection because if it was it would do it at all speeds, plus it hardly didn't do it anymore with the old VSS. I only changed it becasue of the ABS light and I was making my back brake lock up on wet pavement if I had to mash on them. Now with the new one the brakes are fine, just got the speedo jumping above 50 mph.

 

I cannot recall if there is a speed module on our trucks or not.

But yeah, even on the cluster it could still be your issue.
Might even be something inside the cluster.

 

When mine did the bouncing , it was a bad wire .. I had to feel the wire to find the bad spot . The copper had broken inside the insulation..(soft spot)

 

Do you recall where it was at? Was it by the VSS or behind instrument cluster?

 

It was between the frame & the Vss ...

 

Thnx...I guess that's what I will be doing this weekend!!