How Can I Reset the Theft Deterrent Alarm on a 1997 Toyota Avalon XL?

To reset the theft deterrent alarm on your vehicle, start by reconnecting the battery and waiting for the alarm to silence. Then, insert the ignition key and locate the red button on the left side of the driver's dashboard. Make sure this button is set to the "OUT" position. Next, turn the ignition key to the "ACC" position. While holding the red button in, turn the ignition key to the "ON" position. You should hear the horn sound three times rapidly, indicating that the system is resetting. After that, turn the ignition key back to the "LOCK" position, and the horn should sound again three times. At this point, your engine should start, and the theft deterrent system will be successfully reset. If you want to deactivate the system after resetting it, ensure that all doors, the trunk, and the hood are closed. Insert the ignition key and turn it to "ACC" again. Push the red button to the full "OUT" position, then turn the key back to the "LOCK" position and remove it. This will deactivate the system. Keep in mind that sometimes the system can enter a protection mode when the battery is disconnected, depending on whether the doors are locked or open. This condition isn't well documented, but the reset procedure I provided should help you override it.