My lightning is 2001 stock. I notice the problem this year where the security alarm is no longer functioning. In the past, the alarm was sensitive but it worked. Now, the alarm does not go off if I gently hit it to activate it. The head lights and rear lights go off but there is no sound. The truck runs fine but I'm just worried because this a security risk. If someone breaks in then I won't be notified by the alarm going off.

I ask several of my friends who work on cars and are semi mechanics. One of them mentioned that it could be a problem with the alternator. Another one said it could be the battery for the truck.

I'm clueless to the mechanics of a truck but I thought it was probably battery for the security horn or maybe replacing a fuse from the fuse panel inside and outside.

 

Is this aftermarket type alarm? Most likely, the horn/siren is malfunctioning. It is a common problem to have the stok horn go out. It is up under the right fron bumper area. Does the horn work?

The stock system only makes a horn sound after a second hit on the lock button.

Aftermarket alarm sirens can become wet or wires get cut/loose.