Cadillac STS Forum - 2005 through 2012 Discussion, $4 Fix to Door Handle Micro Switch Woes in Past Cadillac Vehicle Discussion; Here's how you can replace those pesky switches:
Follow the handle removal steps in this thread: http://www.cadillacforums.com/forums...ement-how.html
If you determine ...
Remove the microswitch harness from the handle. With a fine screwdriver, remove the potting the bottom of the switches. Draw a diagram of how the wiring looks, and switches are placed in the holder. Once you have removed enough potting, the switches can be pushed out of the holder by pushing up on the bottom (wire side of the switches). Unsolder the wires from the switches (you made the diagram, right?)
Lastly put potting compound on the connections. Do not use silicone as some kinds can damage the connections due to acid released during the cure. My low tech potting compound was a hot glue stick (it seems to work fine). It may be beneficial to first place the switch harness back into the handle assembly, to check how the wires exiting the switch housing relate to the handle body before potting (otherwise the wires may not clear the handle body).
Installation is reverse to removal, make sure to read the note about this in the removal instructions posted at the start of this thread. Grease all plastic to plastic interfaces, it makes reassembly easier.