RKE fob modification

Problem: The "panic" and "trunk open" buttons on my '97 Buick's Remote Keyless Entry transmitter (key fob) kept getting pressed accidentally, which caused embarrassing horn honking (from the panic button), and a trunk full of water (after the trunk popped open during a downpour).

Attempted solution: I cut the Panic button out of its circuit, and spliced it into the trunk-open circuit, in series with the trunk-open button. The intended result was that the panic alarm would be permanently disabled, and to pop open the trunk would require simultaneously pressing both the trunk-open button and the former panic button.

What went wrong:
1. After the modification, the range of the fob was greatly reduced, to less than half its former range. I initially suspected a weak battery, but replacing the battery didn't help.
2. After working for about 5 months, the modified fob stopped working entirely. Replacing the battery did not revive it. It seems to be completely dead.

Questions:

  1. Why was the range so greatly reduced? Was the circuit trace that I changed acting as an antenna, and I ruined the antenna design?
  2. Where is the antenna in this thing, anyhow?
  3. Why did it stop working entirely, after five months?
  4. If I want to make this modification to my remaining (unmodified, and still working) RKE fob, what should I do differently?

 

The assembled key fob (GM/UTA 25668603)


(click on the photos for close-ups)

 

Unmodified:

 

Modified:

 

Dave Burton
H: 1-919-481-0098