2010 Mazda Mazda3 - Electrical glitch sets off alarm and more

2010 Mazda 3 Sport GX Auto

Car alarm (lights, horn) goes off randomly, then stops (battery checked, all good). Also, door-ajar dash light and interior dome light will go on while driving - hitting door lock button with turn both off.

How do I fix this? I’ve just removed the horn fuse so at least it’s not annoying the neighbours, but the issue still occurs.

There is a malfunctioning door ajar switch. If the security module detects a door ajar while the alarm is set, the alarm will sound. Identify which door is causing the door ajar warning and replace that switch or door latch.


Concur, and it is probably the driver’s door switch that’s gone faulty.