1996 Chevy Truck Failure to shift

Have you had it serviced? Always an inexpensive attempt at a fix when it comes to automatic transmissions. Is the check engine light on? does the speedo work properly? Could be a shift solenoid problem. Have the PCM scanned to see if it has stored any failure records for the trans

Thanks for the reply. The trans was serviced approximately 9 or 10,000 miles ago. Don't remember the exact mileage. Done at Chevy dealer. Fluid, filter and whatever they do, I guess. Tow a travel trailer, so I wanted to make sure the fluid was changed. Speedo works properly. Check engine light's not on and never came on. I plan to check the OBD's anyway. Problem seemed to start with the colder weather. No temp sensors anywhere other than inside the trans? How about the throttle position sensor? I did set the throttle speed up, as the engine was idling too low after I had the intake manifold gaskets changed at the Chev dealer because of an anti-freeze leak. Thanks, Greydaddy. :?:

The idle wouldnt change the trans shifting.Could be something internal or the position sensor on the side of the trans isnt seeing that it is in OD.Changing the idle can cause a check engine light if the PCM cant do what it wants to with the idle speed due to the minimum idle being set too high