Speedometer and overdrive not working

[frank1]

My overdrive shifted down and my speedometer stopped working at the same time, while driving between 50-55 MPH. Truck will not shift into overdrive at any speed! Where do I start to look? PCM, TPS, new speedometer cable or all of the above? Has this happen to anyone else? Thanks, Frank (1992 W-250, Extended Cab)

 

[ZedMikey]

Sounds like a VSS (vehicle speed sensor) problem. Check that bad boy in your transmission (if 2WD) or tcase (if 4WD).