My overdrive will not start working until the enging gets really warmed up, ususally after driving for 15-20 min in the morning. The car has only 135,xxx miles. I have kept the fluid changed but it probably needs it now. The level is good. I know its not the solenoid or circuit because once it starts working it works all day long until it sits for several hours overnight. I guess it could be a relay problem. I also checked the trans cable at the throttle. It moves freely and I can hear it "tick" when I snap it. I know that means the lever that its attached to in the trans is going back to its relaxed.... home (for lack of a better word) position.

My 85 started doing this and nothing would fix it until I replaced it with a known good trans. I had replaced the cable and the solenoid and repaired the wiring. I could hear the solenoid on the trans click when turned on and off. I used the same solenoid with the new trans and it worked fine. I have not listened to my 91 solenoid when its not working so that is something I should verify.

I feel like it must be a spring or a check-ball in the valve body thats getting stuck or sticky or weak.... something.

Any help is greatly appreaciated.