Shift Solenoid or Valve body issue

[packetstormin]

So my 94 has been having an issue with not shifting out of third gear. The issue doe not occur all the time.

Seems like a restart usually will fix it after it has been driven for awhile.

Truck has 231 thousand miles on it.

Currently, I am driving it with the cdl locked because the rear drive shaft is off. I don't remember if the truck did it with the cdl unlocked.

Like I said it will go through 1st, 2nd, 3rd gear and then wont shift in to 4th.

Does this sound like a clogged valve body or a bad shift solenoid?

Any opinions are appreciated

 

[packetstormin]

Bump for help

 

[powderpig]

If you have the Factory service manual. It has a section on the transmission with full description on how to inspect the electrical section of the tranny as well as some insites on the computer. This tranny is mostly shift by computer, so not too much on the valve body being bad. I have replaced a few of the soleniods over the years with great suscess, but typically I first do the procedures in the book.

 

[rove_mcanus]

There is a lot of systems to check with these. As suggested get the fsm as it has great detail on diagnostic procedures.

A few things come to mind though. There is a cold temperature overdrive lockout. That is the 4th gear will not be selected if the engine temperature is low. A problem in any part of that circuit could be a cause.

Overdrive on/off is selected electronically. A problem with the switch or wiring there could be the problem.

You can determine if it is an electronic problem before the transmission by checking voltages at the solenoids whilst driving through the gears. Toyota have a tool for doing that on a road test. However it can be done on stands or a hoist. It's simple, and again the FSM will tell you all you want to know.