Car Alarms: 2001 ford f 150, ford f 150, key cylinder

Question
It is a factory alarm and the horn starts to go off I thought it might have something to do with the ignition key
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-----Question-----
after using key fob to open door and starting my truck the alarm goes off. I have to turn the truck off turn off the alarm again then pull the key out and start over again it does this several times before operating properly
-----Answer-----
Is this a factory alarm or an after market alarm?  The alarm either way should disarm by using the key fob.  If it is after market I recommend taking it back to where it was installed as most places offer a lifetime warranty on installation.  When you say the alarm goes off, is it a siren or the vehicle's horn?

Answer
There is a dk.green/purple wire in the driver's kick panel that works as the factory alarm disarm wire.  This wire goes to ground when you turn the door key cylinder to the unlock position.  Try grounding this wire, if this works, I would recommend adding an after market keyless entry (or maybe a remote starter to make it worth while), when properly installed this will pulse that wire with a ground when you unlock the doors.