Newbie question. Horn beeps when locking

[Dgnarvs]

Originally Posted by Skrapmot

Mines has done it i changed out the stereo. I like the beep. It lets me and everybody else know the car is locked and the alarm is on

I thought that if the horn beeps, it means the alarm is not fully activated??? I have the same issue and cannot find out why. Doors appear to be closing because the door lights turn off when closed. Don't have a glove compartment so that's one less thing to worry about.

I had it checked by a mate with a Durametric and he suggested that it's the sensor on the trunk. However, the dash warning light does not go off. Could that still be the culprit?

I do have an aftermarket radio/head unit which has decided to not function recently. It just wouldn't turn on! Could that be related to the alarm???