Welcome, and thanks for using Just Answer. I am Cam, and I will do my best to assist you. When you are finished please click on accept only if you are satisfied. I don't get paid unless you do.Please do not accept if you cannot leave positive feedback. I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can. About your vehicle,
This sounds like the typical issue with the security. Most simply bypass it now.
http://newrockies.ca/fullbypass is the unit I use.
According to the person that I bought it from the security system was already removed. How can I check to see if this is true or not. Where is the bcm located and what does it look like. I am not a mechanic but have limited knowledge of my own cars.
The BCM is to the right of the steering column under the dash almost under the heater control.
It will be a black box with 2 or 3 connectors.