Chimes and door ajar problem on 95 Grand Voyager

I've had this van about 5 yrs and it has 136,000 miles on it. Problem started last year when weather got colder, when I drive down my dirt road, every bump causes the door adjar light to flash, as well as the courtesy lights (really annoying at night), and the auto locks snap up and down. In warm weather, there is little problem. This week when cold weather hit TX, it chimes and flashes when turning around (van rocks back and forth on my rough drive), and very often. I tried removing the fuse for the auto locks, but that didn't help. Where is the sensor to operate this? How do I fix it cheap? Thanks for the help. Anybody remember "Plymouth makes it!"?

Daverunaround