amye

Dear All,

I am brand new here and to forums in general, so please be kind to me. I really need advice and don't know how else to find it internet-wise. Haven't found this problem anywhere for my car's model year.

Three weeks ago the alarm started going off on its own. Happened two or three times per week that I knew of (not always near it), thought it was cats crawling over it or a bug in the cabin, but over this past weekend it happened three or four times per day. I tried locking the car doors with the key in the cylinder, alarm still goes off. Last night I left it out there unlocked, don't think it went off but can't be sure.

Brought it to two mechanics today, one specializes in American model cars and has seen this problem on five other Mustangs, all a bit older than mine. Problem with all of them was the trunk microswitch on the key cylinder (hope I got that right). Mine doesn't have a key cylinder, so he and the other are both completely stumped. We pulled the fuses for the normal horn and the alarm horn, to keep it "safe" (i.e. neighbors not keying it or calling police to have it towed) until we can figure this thing out. So now I can only lock my doors manually and I cannot open the trunk at all. So now we are all three making phone calls and searching the internet, they two here in Germany while I scour my homeland's forums and contact a few dealerships near my hometown in Michigan.

By the way we think this is probably related: This past winter my tire pressure warning light, then the door ajar warning light also, started coming on and shortly thereafter going off while I'm driving. Tire pressure fine, doors obviously not being disturbed while driving. Haven't had the tire light come on since the cold weather passed, but the door light is still happily illuminating itself at will.

I'm in Germany, not too many Mustangs in my area, and haven't yet taken it to a dealership because none of the Ford places near me actually have my model/year coded into their computers, meaning to scan my car's on-board is not possible. Also I am really trying to save costs here, and the mechanic friends are the only ones who have ever touched my cars since 2006, I trust them 100% without doubt. Besides, the Ford people here couldn't even figure out how to reset the "Oil Change Due" message (again, their computers have nothing on the 2010 Mustang)...I ended up figuring that out on my own (and really had a "duhhh...." moment that day).

Listen guys, I'm a girl, this is my second GT (first was a '95), I'm the second owner and bought it in 2011. I baby it because it is the only damned tangible thing I own, and it's very special to me because it's the first thing I ever bought for myself with no help from anybody.

Please be kind to me. If you start being snarky like I've seen from a lot of people in all the threads I searched looking for this problem, I'll just have to start all over again in another forum somewhere and meanwhile my poor little horse is sitting out there, unprotected, and probably in pain cuz he's obviously sick somehow and I'm too dumb to help him. And the problem could be spreading still, if it in fact started with those sensors and lights.

What I really need is somebody who has had this problem with a 2010 or newer or experience with it, to let me know what their problem turned out to be and what steps were taken to remedy it. So if you have, or know someone who has, please share some advice with me. I'd appreciate it so much.

Thanks in advance for your patience with me...

amye

...that this is a factory alarm system. If anyone needs further information, please just ask. Thanks again.

JimC

More than likely it is the sensor under the hood. That is the most exposed and will exhibit exactly what you describe when it goes bad. The sensor is on the passenger side, looks like a little plunger next to the fuse box up on the fender lip. Replace that and you should be good.

amye

Dear JimC,

Thank you so much for responding. This suggestion is first on my list of things to try.

Amye

Derf00

dealer can troubleshoot it for $45 bucks. Then you will know for sure and be able to decide if you want them to fix or if you want to do it yourself (depending on what it is).

Had a similar issue with our 06 Escape in that it was related to the factory/dealer installed Ford alarm. The module's ignition circuit had gone bad and was preventing the car from starting sometimes. It was random then became permanent. Took it to them after I exhausted all I could troubleshoot (didn't even think of the alarm at the time since shop manual diagrams don't have the wiring schematic in them for that system). Dealer called me about an hour after they started working on it. $45.