I recently got a 92 D250 Cummins Diesel w/auto trans. The Cruise Control never has worked over the 8 months I've had the truck, but over the months the speedometer/odometer and Overdrive would quit working periodically, when I parked the on an incline and put the truck in PARK without first pushing the Parking Brake on. Usually after a few miles both the speedo/odo and Overdrive would begin to operate normally until the next time I forgot to push the Parking Brake on first. Now the situation is constant: no speedo/odo or Overdrive.

Does anyone know what may cause this problem with the speedo/odo and Overdrive? Could it be the neutral safety switch.

 

Sounds like a VSS (vehicle speed sensor) problem. Look for disconnected wires or a loose sender on the drivers side of the tranny. It is an oval shaped sender w/a wire plug on the outside and a large nut where it attaches to the trans. There is also a problem internally sometimes with the drive tang going bad.

 

Yes, check the VSS. Do you have any other issues in and around the dash? Maybe a bad ground connection in the dash area that the bump of releasing the parking brake is changing? Maybe the main connection to the dash cluster is a bit wobbley? Also, one guy on here had an issue with the parking brake eating through a wiring harness right above it. Something about the teeth on the cog on the lever that were rubbing on the harness. Maybe this? If it's the VSS, you can get it at Napa, part# VSS100, for around $50. The install takes maybe 45 seconds.

 

dodgenstein & Tuckerdee, Thanks guys. I found the VSS location.

If the VSS is removed and replaced, do I lose transmission fluid?

 

No. The fluid will stay in the transmission. If there is fluid coming out, then you've got a seal problem. I have issues with my VSS from time to time. I know because my speedometer starts jumping up and down and the cruise won't work. I just pull it off and hose it down with some electric motor cleaner, let it dry out, then stick it back on. I don't know if it's from transmission fluid leaking out the drive or from oil (I've got a few leaks) flying back from the engine while I drive, but it does get gooey after a while. I did have a transmission line come apart a few months back that let a lot of fluid fly everywhere. That's most likely the problem this time.