96 explorer 4.0 - 4r55e - 4x4. 195,000 miles. transmission rebuilt and torque convertor replaced 20,000 miles ago.
i have had a problem with my torque convertor clutch engaging or staying engaged twice this week.
the first time a few days ago, i was driving on the interstate 70 - 80 mph against a bad headwind. the tranny had shifted into overdrive climbing a hill but couldn't get up enough power to lock the torque convertor. i had the cruise control on and let it keep running at a higher than normal rpm for that speed. then the o/d lite started flashing and continued to flash until i turned off the ignition 10 miles down the road. the TCC wouldn't lock up before or after shutting off the key for the rest of the day (100+ miles) but the o/d lite stayed off. i could still turn o/d on or off normally with the button and the lite indicated this correctly. at home i disconnected the battery and everything worked correctly the next day including the TCC.
two days later, the same thing happened . no headwind this time but climbing bigger hill and lite started blinking which disabled TCC. i borrowed a EZ-Link code reader from parts store and tried to pull trans code while lite was still flashing, but no active or pending codes. the TCC would not lock up for the rest of the day again. however, this time i did not disconnect the battery. when i drove the next morning, everything was back to working correctly including the TCC.
i am wondering if this is normal for the ECU to forget or disregard the previous days problems and its decision to disable the TCC lock-up, just because it sat for 12 hours???????????

one more observation - when lugging the engine in overdrive with TCC locked, just before the TCC unlocks (which feels like a downshift) i can hear a slight rumble or growl from the drivetrain (prob transmission). after the downshift (TCC unlocking) it goes away. if i reach the top of hill before this happens (unlocks) and the engine isn't having to pull as hard, the noise also goes away.

i hope this makes sense. any ideas on what my problem could be before i take it to the tranny shop. they are on the other side of town so don't know when i willl get there, plus it is out of warranty anyway.
thanks.

 

Great site all! I am currently having the same problem that ssjerrys had in 2004. When the engine/tranny are cold, it seems to shift fine. After it warms up, I either have to stop accelerating (< 10% throttle) around 50mph to get it to lock or I have to modulate the throttle between 5-50% at 55mph to get it to lock. If I drive too long (1-4 minutes?) without the TC locking, I'll get the flashing OD light and it won't lock until the car is turned off for a few hours.

156K miles, original owner.