Transmission not going into gear when warmed up?

[2g2fast]

Hello everyone i have a 97 GST Automatic and im having some Transmission issues, The car shifts perfect when its cold and will stay in gear but once its warmed up if i put it out of gear it doesnt wanna go it to any gear except neutral and park...

Could this be the TCU?

 

[97spyderman20]

Might sounds dumb but did you check the fluid levels once it is warmed up?

 

[delta448]

How long since the last fluid and trans filter change?

Might be time to invest in a better trans cooler. Heat is the biggest detriment to A/T fluid life.

 

[bluehaze420a]

There is also alot of threads on this topic. It always helps to google search but under dsmtuners: in the search bar. It is a little hard to find excatly what your looking for on here so i find it easier with google.

 

[2g2fast]

How long since the last fluid and trans filter change?

Might be time to invest in a better trans cooler. Heat is the biggest detriment to A/T fluid life.

I havent changed it since i bought the car but i haven't been driving it because it didnt pass emissions which im fixing right now, The Trans was rebuild 3k ago and the fluid looks good and smells fine.