Recently when I locked my 2005 MDX and went to activate the factory alarm - usually my lights flash and horn chirps once, this did not happen. Nor did the blinking red light on the door indicate that the alarm was activated. Yet, when I unlock the car, the lights give their customary blink. I looked on the fuse box cover but did not notice a separate fuse for the alarm system. Is the alarm piggybacked with another system on a fuse? Funny thing is that I have not noticed any other electrical malfunction....

 

Check to see if any of the doors are open especially the trunk.

 

Have checked doors/rear hatch all are fine. That's one thing I like about the MDX - the display on the dash is very visible and lets you know when something is not completely closed