Troubleshooting Trunk Ajar Light Problem
 

I have a 2001 SL2. Recently, I have had a problem with the trunk ajar light coming on. When I go over a bumpy road it flashes on and off, so obviously it's a loose connection. I also get the three-beep warning when trying to lock the car from the remote. If I slam the trunk lid down a few times, it corrects the problem.

I am handy with a multi-tester, but I would like some advice on where to start to diagnose where the problem is and how to fix it.