If your vehicle is showing car alarm goes off randomly while parked, here are the most likely causes and the parts you'll need to fix each one.
A dying battery causes voltage fluctuations while the car is parked. The vehicle's security system interprets this sudden voltage drop as an attempt to tamper with or disconnect the battery, triggering the alarm.
The switches that detect if a door, hood, or trunk is open can fail, corrode, or get dirty. If a switch momentarily loses contact, the alarm system thinks someone is prying the vehicle open.
A dying battery in the key fob, a stuck panic button, or internal fob water damage can cause it to transmit random panic signals to the car while sitting in your pocket or on a counter.
If an aftermarket alarm was installed, the shock sensor may be set too high, causing wind, loud exhausts, or passing trucks to trigger it. Poor wiring splices during installation can also cause false triggers.
The BCM acts as the brain for the vehicle's security and lighting systems. Water intrusion (often from a leaking windshield or sunroof) or internal electrical shorts can cause it to erroneously activate the alarm.