My speedometer is acting strange. It jumps 20-30 mph back and forth when at a steady speed. It also seems to read high and will sometimes bounce up and down when the truck is idling. It worked perfectly fine for quite some time. I had a similar problem before and replaced the vss which seemed to solve the problem. This time I put on a new vss and it does the same thing. Have any of you ever had this problem? Any ideas? Thanks.

 

Check all your grounds and your speed sensor wires to make sure they are not rubbing somewhere. Also your speed sensor reducer. Make sure the VSS is spinning in the gear speed reducer correctly

 

Hate to keep asking these questions, but I cleaned my connections saturday and got the speedometer to go from barely to not reading to reading right for a few miles. Then it started to jump and is now jumping and reading excessive speeds. Is there anything else I should try? In the past I have put a new vss on and it worked, but if it is that again why is my truck eating speed sensors. I don't completely understand how this works so I can't accurately trouble shoot it. Please help, it is getting aggrevating.

 

The speedo drive gear on the getrag is sandwiched between 2 spacers. the only thing that keeps it from moving is the nut holding the rear drive shaft coming out of the trans. Try droping the front of the drive shaft and tighten that nut. It needs to be very - very tight. I can get you the torque specs if you want.

Good Luck

Bob

 

Specs would be great, however I have a 4wd does that apply for the np205 transfer also?

 

Yes - in fact that was where the problem was first discovered. The yoke nut torque spec. is 280 ft/lbs.

Bob

 

Is there anything I should do special or just block the wheels leave in gear, take off u joint straps and tighten the nut?

 

That should be all you need to do. The nut may not move much but if that's the problem it wont need to move much to solve the problem - mine didn't. Others that I have posted this for have also said that theirs didn't move much either.

Bob