Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
It's a lot more than just that, I did it once on a truck I was parting out, and had to use a system of relays that worked with the latching design to sequentially work in an order to allow the BCM to see the key resistance.
HP tuners can help you if you are trying to make a standalone setup to remove antitheft
