I towed my 10K trailer this weekend for the first time in a few months and found I can't get the truck out of overdrive.The overdrive off switch doesn't work and the truck won't shift from overdrive to third under load by itself so when I did the big hills I had to pull it into second.All the wires were pluged in the back of the switch and I checked the fuses,any ideas?? Thanks.

 

i'm not an expert on the subject but from what i have seen on here overdrive issues seem to be related to the throttle position sensor (TPS) if that is the case, this link is a cheaper fix than a new tps

https://www.dieseltruckresource.com/...threadid=42003

hope this helps!

 

If you're not shifting in O/D while under load it's most likely that the TPS only needs adjusting. If it's never shifting into O/D, then it could still be your TPS, or perhaps your Vehicle Speed Sensor. If the VSS isn't working you'll have no speedometer as well.

 

The speedometer works fine now its warm weather(didn't sometimes when its cold).How do you adjust the TPS sensor??

 

Here's a good description on how to adjust the TPS from Piers Diesel: TPS

 

Hey thanks guys I'll give it a shot.