Glad I found this site..Learned some good stuff browsing through..
What initially drew me to this site is the following problem:

I just bought a 2002 Explorer XLT.
This is my 3rd X, but the 1st one I have
bought used. The dealer was NOT a Ford dealer
and had just one fob. I need to have 2 fobs and
have considered buying from eBay rather than from Ford.
A coworker happened to have a left over fob from an older
X that he had sold and he said "Here, you can have this
one, give it a try...you can read how to program it in your
owners manual". I figured I would give it a shot (FREE IS GOOD)...
However, when I followed the simple instructions (turn ignition 8x between position 2 and 3 within 10 seconds than push any button on remote) nothing happened...The free remote did not work...No big deal, it probably was not the right model fob,...MY BIG PROBLEM IS: NOW MY ORIGINAL REMOTE IS NOT WORKING...Any thoughts?

I appreciate any advice offered.

VTY,
Steve