Iposted this in another forum and got no responce . Maybe this is the place.

I have a 91 d250 a couple years ago my throtle pesitioning sensor went bad. I read an article about bypassing it useing a valume switch and this worked for the last couple years, The other day my speedometor did not work and my overdrive does not work.
Does anyone have any sugestions?

thanks in advance

 

The VSS probably shot craps.
This is located on the tail shaft housing of the transmission.

If the VSS malfunctions, there is no signal to the speedo.
The VSS also tells the ecm to allow the overdrive to work.

Mark.