99 Suburban Keyless Entry Problem

My parents own a 99 Suburban. When they bought, it they told them that the alarm was factory. They also told them that it was supposed to arm when they turn the car on. You have to disarm it before it will start. I'm a girl, but I'm no idiot. I have never heard of or seen any alarm that arms when you turn the car on. The lights in the car don't turn on when you disarm the alarm nor do the headlamps turn on when you arm it. The only thing that works on this blasted alarm is the stupid horn. Can anyone help?
I don't want to try to bi-pass it because I did that in my firebird and created a load of electrical problems in my car. I tried unplugging the pwr hoping by some slim chance that the brain just needed to be reset, but of course that didn't work. Any suggestions?

If only the horn blows, most likely the alarm is factory, do they have the keychain transmitters remotes? If they don't have the remotes they will have to buy them and have them programed to the vehicle. You can do it yourself, if you look around in the forums for the reprogramming proceedure. The remotes won't work until the vehicle "learns" the frequency they operate on.

If only the horn blows, most likely the alarm is factory, do they have the keychain transmitters remotes? If they don't have the remotes they will have to buy them and have them programed to the vehicle. You can do it yourself, if you look around in the forums for the reprogramming proceedure. The remotes won't work until the vehicle "learns" the frequency they operate on.

thanks for the reply, but I did talk to a tech and after some checking the dealer lied about it being a factory alarm. It's actually a very crappy aftermarket alarm. Not to mention after looking at it more and looking for what the tech said, it seems as if the alarm was installed wrong. It does have transmitters that don't always work, but the tech said I won't know if the actuators in the door are defective until I replace the alarm "brain" because we've already replaced the batteries in the remotes. Thanks again for your info.