I own a 05.

Yesterday evening my car alarm started going off for no reason... However, it didn't sound the same. For some reason the horn was honking 3 fast 2 slow and repeats. It took three presses on the panic button of the remote to stop it. This morning it did this three times in an hour at work so I took it intoa Ford Services at a dealership today. They couldn't find anything wrong and said that my alarm was third party (I bought the car when I lived in CA but now live in SC so it isn't the same dealership).... They said that sometimes when the window isn't rolled up it would change the pressure and it can go off. Windows were rolled up tight. I bought this car brand new with 9 miles on it and never made any mods to it. The carhas less than 20k miles on it and this is the second problem that has poppedup. Everyone that heard the horn thought there was a short somewhere. When I press the unlock button on the remote the horn goes off three times now. Notice things are happening in 3s with this problem. I'm so frustrated with this issue that if it continues I'd either disable the car alarm or buy a new car. I know for sure this will be the last ford I ever buy (there have been other problems).

 

check to see if your passenger side floor is wet. You may have a water leak that has intruded on some wiring or control box. This is a know leak area on 05-06. Just a thought cause I've heard this leak has caused some electrical problems.

 

If you bought your car new and the invoice does not mention any dealer installed alarm, Ford is responsible for the problem, so insist with them, talk to a manager or try a different dealer, if it doesen't work try the better business bureau or something but they must fix the problem whether they like it or not.