Gentlemen, It's over 8 years since the very first posting in this subject, and God is my witness, IT WORK!!!!!!!!
I was so enthusiastic, that I forgot to take pictures...
But just to emphasize what "hunttom" writes above; the system is totally mechanical, EXCEPT the latch, which with the help of a little solenoid, remains locked in the upper position, with a little fluctuation. The solenoid is electrically connected to the sensor. All the sensor does, is sending a short electric signal when it senses a hit in the rear. That solenoid drops down, releasing the latch and the very strong spring, that pushes the front of the headrest forward. That latch is the source of all evil. It has 2 positions up and down. Normally, inside the headrest, it's locked in the up position, it'll jump down on sensor signal and in many cases, will remain locked, facing
down.
I used the voltmeter's wires, stuck them at the bottom of the headrest post (where the black plastic edge is). lifted the cover in the trunk (I didn't know it has a hook to leave open!), removed the cover from the "+" on the battery and connected to the battery. you hear a "click" and WHILE POWER IS STILL CONNECTED, push the latch to the up position. No difference which polarity. That's all.
I put the headrest on the stairs with a piece of cloth, worked as per the TSB in the beginning of this thread (message #2), and when my knees weren't enough, I simply "stood" on it with my knees. 195 lbs worked!
The dealer wanted $135 to try, with a 50% chance of succeeding. Upholstery guy, wanted $60. New one, $306. Couldn't find black used...
Now I'm happy!
Thank you so much to "Dimitry", "hunttom" and "easy ed".
You guys are awesome!!!