I was driving to work this morning and truck shifted fine. Got off the interstate and onto the local highway and truck would not shift back into OD. Parked, checked fluids and let it cool. (trans temps were normal on the Juice monitor 148deg) Got back in and drove it another 10+ miles and still cant get it to shift into overdrive. Other gears seem to be shifting fine including Reverse.

Could this be the Solenoid or do I need to find a new Tranny?

Thanks,
Josh

 

Several different things can cause that. Need to see if there are any codes related to the solenoid. There is a snap ring that can break in the overdrive unit causiing similar conditions. Typically you will find a piece or two of it in the pan if it does. There is also some wiring inside and outside the pan that can cause it, but they will usually set a code. Get the codes checked and report back.

 

Thanks... I just checked it with the ign switch deal and there are no codes. Just says "P done"!

 

Hmmmm......gonna need a scanner to read inputs and outputs to see if it is trying to engage overdrive, or if its not trying to engage, why not. There are a lot of factors used to determine O/D engagement. Trans temp, speed, throttle position. Not gonna be easy without some sort of scan tool.

 

It could be as simple as a adjustment to the brake peddle sw.

 

^ That is VERY possible. Forgot about that! There are 2 circuits inside of it though. The lamp circuit may be fine and the cruise/trans circuit may be acting up. Does the cruise work?

 

While the brake lamp switch would be a very good place to look for "no lockup", it would not hinder the trans from achieving OD. I don't have much to offer at this point as you've entered "scan tool, good book, DVOM" territory.

 

I do think that the OD is shut off by the brake sw also , same with cruse .

 

Thanks for the ideas guys. I exhaused everything and the tranny was shot! Had it rebuilt and added a Billet TQ so now that I have a warranty I can beat on it a little...