Security Light On In Message Center

[swovvster]

2002 GMC Sierra 2500HD Diesel with Allison Transmission

 

The original owner installed a remote starter on the vehicle. When the remote starter started giving him problems, he removed the remote starter. Ever since then, the security light is on. The vehicle runs with the light on. I replaced the ignition sensor (at the advice of a mechanic) and $350 later, I have a new ignition sensor but the light is still on. While the truck is running, I attempted to turn the key forward ever so slightly which will turn the light off. When I did so, the security light went off and the battery signal (red) came on momentarily before going right back to the security message being on. The message center will display other messages as well....low fuel was flashing once. It took turns between the security and low fuel. Any hidden secrets to get that security light off? Thanks Chris