Jeffrey Pasqua said:
I had to have one changed and they could not do it in a timely manner so I learned on my own.
Changed quite a few since then. Carefully remove the silicone, circut board is about 3/8" down. Radio shack sells the batteries, the are like half AA size and about $18 bucks. I have an extra that I soldered aligator clips on. I connect the aligator clips to the lead to keep the system powered up, unsolder the old battery and solder the new one in. McMaster car sells the anticorrive silicone (3m makes it).
Funny thing is I changed one once where the battery was completely dead and did not put a jumper battery on it, it worked fine in the end without any special code or flash, but I would not go that route if you dont have to. They could have changed that from year to year.
Good luck and call me if you need anything.
Jeff - do you recall exactly which battery it is?