2001 chevy alarm

I bought my truck about a month ago. When I use the key pad to lock my doors i cant use the key to unlock or start the truck or the alarm goes off when i start it. If i do use the key the alarm goes off and wont quit untill i lock the doors and use the key pad. Also if i lock it from the inside and I use the key pad to unlock it the alarm goes off. How can i fix this?

When you refer to the "key pad", are you talking about the factory keyless transmitter?  aftermarket alarm?  It sounds like you have an aftermarket alarm.  Does the horn just honk or does a siren go off.  If there is an aftermarket alarm, then it sounds like it is functioning normally.

the way i understand what you are saying, it sounds like the unit is working properly.... you have to use the remote to both arm and disarm the system, dont use the remote and then the key, or the lock switch and then remote... the brain the remotes are tied to remember the last function that THEY activated, then dont know when you use the lock switch or keys.......Kevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979

Thats correct. do you know what kind of alarm it is?  Is there a name on the transmitter anywhere?

sorry...I didnt pay attention to whom the post was from.

it is the stock alarm but the previous owner replaced the key pad with an after market. I guess i should just go to a dealership and buy a new stock keypad. they are kind of pricy though. 35 for the remote and 65 to program