Like other car alarms, the Toyota factory alarms are used to deter thieves from stealing the vehicle. However, if you lose your key fob, find the alarm too sensitive or want to replace it with an after-market alarm, you need to disconnect Toyota's factory alarm. It's not difficult to do.
Find the switch used to disable or reset the alarm. The alarm in Toyota vehicles has a box beneath the dashboard, near the hood release, that has a toggle on it. Once you find the toggle, put your key in the ignition and start the car.
Override the alarm. With the car started, flip the toggle three times. You should hear the alarm chirp once, indicating the alarm is disabled.
Find the alarm fuse and remove it. Toyota vehicles have two fuse boxes. One fuse box is under the driver's side dash and the other one is next to the battery, but the alarm fuse is typically in the fuse box under the dashboard. If the fuses aren't labelled, refer to the diagram on the fuse box cover to find the right one. Then, use a fuse puller to remove the fuse without damaging the fuses around it.