I replaced the drivers door lock actuator with an actuator from a 1998 accord.
Both rear doors need actuators which I have yet to replace. The passenger door lock is working.

The good news is that when I lock the door with the key fob the alarm is armed. I lock the drivers door manually and the alarm arms. I open the lock with the fob and the alarm disarms. So it appears as if the security system is working fine.

The problem is if I use the key to open the door the alarm goes off. The key starts the car so I don't get what might be causing this. Once the alarm is set off, I hit the fob unlock button with door open and the alarm shuts off. I tried using my wife's key and the same thing happens. Both front and drivers door switches appear to be working normal and controlling the dome light. I swapped the the switches but got the same result. I'm stumped.

 

Per the FSM you could have a faulty driver's door key cylinder switch, poor ground, or open in the wire