Quote Originally Posted by modular93fox View Post
You need to reset the security code in VATS.
1. Turn the key on to start the engine, then release the key to the ON position.
2. The security light will flash for 10 minutes then go off.
3. Turn key OFF after security light has stopped flashing.
4. Leave the key off for 10-20 seconds. Not sure if you have to wait but it won't hurt. Repeat steps 1 to 3 for 2 more times for a total of 3 attempts. The vehicle should start on the 4th attempt. This procedure takes at least 30 minutes. The battery should be fully charged and deliver more than 10 volts.
You know the real procedure. It doesn't always work on non-transponder vehicles though (no chip in the key)

on for 10 minutes, when the security light goes out turn it -quickly- to the off position and right back to the run position with no delay between, 10 more minutes, off and on again, after the third 10 minute wait turb it to the off position and wait a few seconds but don't take the key out. IT should start right up.