John I agree that they went to the electronic lock-up with the solenoid for better control of when to lock the conveter since the PCM basically moniters everything. It only makes sense the PCM can control lock-up better then the older hydraulic way. The solenoid is energized when the trans converter locks and deenergizes when it unlocks. My training book even says..................Part Throttle unlock will happen between speeds of 40 to 55 mph. It watches for the manifold vacum to go above 20 inches or below 3 inches of vacum in the 40 to 55 mph range. If this happens the computer (PCM) will deenergize the solenoid which vents line pressure going to the lock-up valve. The lock-up valve then goes to its unshifted posistion and unlock will occur. Lock-up will reoccur when vacum comes back down to 18 inches or up to 5 inches. At those points the PCM will energize the solenoid so line pressure will shift the lock-up valve and lock-up will reoccur.

I am not trying to be a smart a$$ as this is just what it says in one of my Mopar training books. It also says how the solenoid deenergizes at idle and WOT to unlock the converter. I dont mean to offend anyone and I apolligize if I did. Ron