Does my 89 thunderbird have a stock alarm and if so would it interfere with an aftermarket alarm that i want?

Answer 1

A stock alarm was an option on the '89 Thunderbird, so yours may have one. To test, open the door (with the window open), lock it with the power lock button, then close the door. Wait one minute, then reach in through the window to unlock and open the door. If your horn starts blasting, then you have a factory alarm; if it doesn't, then you don't have anything to worry about.

Factory alarms don't often cause a problem with after-market alarm systems; there's usually a way to disarm the factory alarm at the same time as you disarm the after-market one. In the Thunderbird, there's a wire coming from the door lock switch that can be pulsed with ground to disarm the factory alarm. Most after-market systems will have the ability to do this at the same time as the new alarm is disarmed.