Im, looking for some suggestions or common problems before I dive into this.
Driving at any speed my speedo is bouncing all over the place and sometimes at a complete stop its reading 20 kmhr. I have a new vss sensor installed. Also when I set the cruise controll it takes off like a raped ape. Any help would be appreciated.

 

Check the cluster ground.

 

Where's that ??

 

also check that wires at the vss plug have a good connection. I chased speedo problems for a while, and the hole time my issue was a bad wire in the factory plug at the vss. Mine never acted as crazy as yours though.

 

Well not knowing what year truck you have or even if it is a Dodge. Its kind of hard to say where the dash grounds are.

I am going to assume it is a 1st gen Dodge. If it is an IC'd truck it is located on the back metal support frame behind the dash. Reach up behind the dash on the right side of the column. Just behind the OD on/off button. The grounds are held down by a 1/4" headed metal screw.

If the truck is nonIC'd it is behind the cargo light swtich in the same area.

Also remove the 10 gage wire from the raditor support that comes off the negative battery terminal. Sand the raditor support where it bolted down and then reassemble.

 

thanks for the info

 

i had the same trouble and I redid my speedo ground and am in the process of upgrading to L.E.D's
(found in the "sticky" thread)



I also had i chaffed wire at the fire wall - driver's floor pan, that seem cut through all but 2 strands in the vss wire.

fixed my speedo right up (and my overdrive)