Unlock the driver’s side door to deactivate a car alarm system, and examine the car for any signs of attempted theft. If the horn sounds three times, this indicates the alarm was triggered.
First, ensure all the doors are closed. Start the car with the key to make sure everything is functioning normally. Remove the key from the ignition switch, and lock the doors using the remote transmitter. Check to see if the lights in the instrument cluster are flashing quickly. If so, wait a few seconds for the alarm to rearm itself.
If the light illuminates but does not flash, check to be sure all the doors are closed. If the illumination continues, check for broken windows or other problems that require fixing. If the light starts to flash slowly, this indicates the alarm resetting is complete and active.
To disable the alarm without a remote, insert the key into the ignition, and turn it to the ACC position. Locate the alarm transmitter system, which is usually under the hood near the windshield or under the driver’s side dash near the ignition cylinder. Press and release the toggle switch on the system repeatedly until the LED light turns off and the system chirps to confirm the alarm system is disabled and ready.