is it just time for new alarm?

Hello to all I've been having a problem with my alarm lately and I just wanna know if it's time just to replace it or is there a fix? Ok first the alarm is a prestige aps-997n I got it installed about 4 years ago when I brought my 1999 tahoe and it has worked great and served it's purpose window got smashed in 3 years ago and someone tried to steal my radio and the alarm scared the off after that incident I took it back to the alarm shop and put a d.e.i motion sensor and air horns to the alarm but recently it's been going off at random in the middle of the night and when I lock it it tells me the door is still open or I will lock it and I will hear the door locks pulse again and the warn away will sound. If someone can help me it would great thanks

Depending on how the power is being applied/fused those units can suffer from excessive current draw while being used causing some carbon build up on the internal components. Relay contacts etc. Take the unit out and smell around the edges where the wires plug into. If it smells burnt at all replace it immediately. Any 997 unit prior to the 997E revision will plug directly into your current install.

997E requires a few wires to be changed to a new harness and a new antenna.

Those trucks should have at least 2 30 amp fuses on the main 6 pin power harness. In some cases I have had to put 2 40 amp fuses in because of the aging blower motor etc. DO NOT exceed 40a on a single rail of those remote starts. Say if it were blowing 40a fuses you would need to bring battery power in and use the remote start to control relays for each ignition/accessory wire. Crazy, but I have had to do it a few times.

You also want to consider grounds especially on an older GM vehicle. They weren't that great in 99 and they sure haven't gotten any better since then.

To master and control electricity is perfection. *evil laugh*