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TL;DR: key fob not arming/disarming alarm and have to do solenoid screw driver start.

I've been having an intermittent stock alarm issue with my 2000 F-150 (4.6L V8). Usually the alarm is armed with locking the vehicle with the key fob or hitting the power lock on the doors. If I manually push the lock down, that pops up and down in the door, the alarm won't arm. Also, if after using the fob to unlock the truck, there is a couple of minutes window to start the truck- if not started within the window the truck cannot be started until the fob is used to unlock once again.

The problem:

Last month I ran an errand; got there fine and locked my car. Upon leaving I tried to unlock my car doors with the key fob, but to no avail. I unlocked the car door manually with the key and immediately the alarm went off, the ignition was also disabled (wasn't able to start the truck when turning ignition with key). I cut the ground wire on the siren to stop the noise. Put key in ignition, set to run, then was able to do a screw driver start on the starter solenoid. Drove home, and somehow the problem fixed itself (I also reconnected the ground wire on the horn after arriving home); I cannot recall if the fix was immediate or if it occurred a day or so later.

This last weekend the same issue started again. I got out of my truck after arriving at the grocery store, and went to use the fob to lock the doors and they did not lock. Usually when arming the alarm, the doors lock and there's an audible chirp. I drove back home and parked the truck- I knew not to lock my doors with the power lock on the door because then I would have to deal with the siren blaring, so I manually locked the door lock. This allows for me to get in my truck by unlocking manually. At this point I am able to start my truck with the ghetto screw driver start…

I assume there is a faulty wire/contact/solder joint somewhere in the circuitry, due to the nature of the issue and how it fixed itself the first time. The roads in Houston are terrible and maybe something wiggled loose when driving.

First time this happened I did some trouble shooting and verified that the following were not the cause:
-Door lock actuators are working as intended
-Used a second key fob (both key fobs have new batteries)
-Car battery was not changed and still has adequate charge (as I am able to screw driver start)

I did not reprogram the alarm system, and the fact that the remote somehow started working after the first time would make me think that reprogramming the alarm system is not necessary.

I’ve got a voltmeter and a very basic understanding on how to use it. I usually fix everything on my truck, but am looking for direction on this.. Any help is greatly appreciated!

 

Using the door lock indicator to lock the door won't set the alarm. Its desgined that way....

 

Patman,

I should have stated that I understand the alarm isn't intended to be armed when pushing the lock indicator down (hence why I am currently doing that to lock my truck).

 

When you used to lock the truck with the remote did you get a loud honk when the truck locked, followed by a softer honk when the truck was "armed"

 

I don't recall it honking. Would chirp twice when locking and once when unlocking. If it was already locked and I hit the lock on the fob it would honk.

 

does it utilize factory remote?

AFAIK factory RKE doesn't chirp at all.

 

You sure that's a factory alarm?