Every once in a while when I start my '09 Platinum S-crew, I get a message on the dash the the rear drivers door is open even though it is securely closed. I'm wondering if the sensor is bad or if it is something else; loose connection, etc...

As I drive down the road the auto running board on that side goes up and down like the door is opening and closing. It only happens once in a while and of course not when I am near a dealer. Dealer says since they can't repeat the problem they can't help me. Is there anything that I can check or maybe change a sensor on my own to solve this?

 

Check to see if the sensor is sticking or it might have a short or some other intermittent electrical issue as well.

 

Knowing the Ford has had issues with the switch in the door latche for many years. I'd just visit your dealer and have them correct this.

The fix for out of warranty folks (probably not many of you yet with your newer trucks) is to spray WD-40 or similar into the latch assembly and work the latch by opening/closing the door a number of times. This often will clean up the poor electrical contact in the switch and fix things temporarily (sometimes the problem never returns).

 

John Deere has had a similiar issue with their riding mowers and the switch that let's the mower "know" that you have the parking brake depressed. This only happens during the colder fall and winter months though.