My alarm started going off today for no reason. It did this a couple of times while I was at work. When I got home I noticed that on the info display it said my rear passenger door was open. I reclosed it and it still showed as being open. I tried pressing in the door ajar switch and that made no difference.

The troubleshooting began and I pulled the switch to see if it wasn't working. Using a multimeter to test for continuity it showed that switch works (it grounds the signal wire when the door is open, and is open circuit when the door is shut). I then tested continuity at the signal wire itself (the one that goes into the switch) and it had continuity with ground. So somewhere along that wire it is being grounded, making the car think that the door is always open.

Now I know what the issue is, the problem is trying to find where along this damn wire that it is being shorted to ground. Are there any common pinch areas where this might happen? I just got this car about a month ago and haven't torn the interior apart before so I'm not too familiar with how all of the door sill plastics come off (or if that's even where this particular wire is hidden at). Any ideas?

 

Check you door hinge where the door locks onto the frame. It is above the door sensor and can be loose. If it's loose then there's your problem. I had that issue on mine.

 

I think you're talking about the same switch that I've already looked at unless there's a second door ajar switch that I'm not aware of. The one that I looked at is confirmed to be working.

The issue happened to pop up during the first few days of heavy rain, now that it's dried out for a couple of days I haven't had a problem so I'm guessing it's water related. I'm not sure where water might be getting in though and shorting the wire out, everything seems dry.

 

Make sure the door latch, held secure in the door, at the jam, by three Phillips head screws, is also secure. I had mine loosen up, which caused the interior light and alert to sound if I pressed on the door (going around right-hand curves, my leg presses on the door).

 

^This.
I had the same thing with my drivers door.

 

Same thing happened to me last week and I replaced the sensor. It still didn't work so I messed with it a little more and found out that the screw that holds it in place does a bad job of grounding it. I wrapped some wire around the screw and tightened it real good. It has not gone off since