I have a 2000 Ford F150. The other day when I went to get in it, the alarm started going off when I opened the door. I tried to start the ignition and it would not work. I waited for the alarm to stop and then tried starting it again and the alarm just started going off. I read the owner's manual and it said that in order to shut it off I would need to turn the key one click to the right for 3 seconds, but I have been unsuccessful when trying this. I don't think it's an aftermarket alarm. Does anyone know the most inexpensive way to go about getting the truck started? Thank you.

 

Is the horn honking while the alarm is going off or is there a siren going off? Do you have keyless entry? If so, what does the remote look like and have you tried using this to disarm?