Ok, if you're standing in the back of the car looking in the trunk, the actual module is on the drivers side of the trunk The Alldata diagram shows the module to be on the passenger side of the trunk.

Either way, if the diagram is wrong, the module i found still says "Compass Transducer" so it can't be anything else.

That is your compass module. I've had repeatative compass issues in my car with "dinging calibration" messages on the DIC all the time, and when I unplug that module using that wire harness it goes away. You have the compass module there my friend!
Archon'* shielding suggestion is your best bet.....but likely you'll have lots of calibration issues to go along with it!

In a 2002, there are only two possible modules mounted under the rear deck. If you have OnStar, there will be one on the right side and it will have a single coaxial cable going into it. The compass module is mounted under the left side and will have a connector with several conductors. These are your only two options. The speakers can cause problems for BOTH of these modules. The difference being that if you don't use OnStar, the adverse effect is of no concern.

You are looking for the module with the single connector and several conductors under the driver side rear deck.

Unplug it...........if your compass stops working.....that'* it...........simple...............!

Now finding a solution.....well that'* where the fun begins! Goodluck.