4L60E Manual Upshifts Only Hot
 

I have a problem with a friend's tranny. I helped him out with it.
Fresh rebuild (1995 TransAm) with all new clutches, steels, bonded pistons.
It had a Transgo shift kit already and everything put back as per Transgo instruction sheets.
After a drive around the block and stopping at the lights, it won't automatically upshift anymore.
It will upshift fine manually.

Thoughts?

either shift solenoids, or the pressure manifold switch.

Thanks.

Only after its warmed up?

with what your explaining to me its like its not down shifting back to low after you come to a stop, correct?
if you have any scan tool with a live data stream, you can watch the shift solenoids.
also you can watch the trans temp as well to see if it shows any problems. ( the trans temp sensor is in the pressure manifold.)
it will also show whether or not the computer is commanding a down shift back to low gear.
there are times that a electronic device can test good and work for a certain length of time, say like a car warming up to operating temp and quit working once the vehicle has gotten hot.

Thanks tnsmith.