transmission won't shift into 3rd or o.d. 1-2 shift is hard.need to shift into 3rd manually at 35 mph. only have this problem when its cold out. if driven for about 5 miles and park for a few minutes it works fine.shifts fine when temp is over 35 deg. trans is the 4l60e

 

change your fluid and filter. Mine did some wierd things while it was cold, changed the filter and fluid and now it's perfect.

 

How many miles on Truck?

 

84,000 miles just bought it used trans fluid looks new

 

I would probaly still do a Filter and oil change and see what that helps at all

 

Changing the filter is really easy. When you do it try and save the factory gasket if you can. Those cork gaskets are junk.

 

something is hanging up in nthe valve body...i'd probably change or get the solenoids changed while its opened up