So my speedo started jumping around awhile back. Truck has been down for quite awhile with the tranny out so I forgot all about it until I started driving it again a couple days ago. When cruising down the road the needle will be steady then all of a sudden drop 5-10 mph for about a second or half second then jump back up again. It'll just do this randomly off and on. Also if you have the cruise control set when it does this the cruise kicks off.

I check the VSS and it looked like it was dammaged by something hitting it so I took the rear diff cover off and found what looked like a part of a clip of some sort in the bottom of it but I couldn't find anywhere where it came from and everything looked good that I could see. I put a new VSS in it and it still does it. I called a couple local speedo shops and they said it's something in the speedo cluster itself and it'd be like $150ish to fix it.

Has anyone had a similar problem? And if so what did you do to fix it?

 

Any metal in the diff when you opened it up? the sensor works like a cam sensor- magnetic- any metal in there will cause issues.

I have also seen wire chaifing cause the same issue, might look over the wire harness.

But if its not causing issues with the shifting and such I would suspect the cluster as well.

 

Yeah no real shifting issues. Just the jumpy speedo. There were a couple of small pieces of metal in the diff but like I said I couldn't see where they came from. Everything looked fine.

I'd like to find a Lightning speedo for it but I've never been able to find one.