4.9 L. At the switch, cut the yellow wire. Cut the brown wire and hook it up to a keyed positive wire ( a wire that's hot when key is on ). Now if you've disabled some of the smog junk ( like me ), clip the red wire and cap it with a twist nut. The check engine lite won't come on anymore. I think that will disable the injector blower fan too, but i removed that stupid thing a long time ago. Irregardless, the red wire doesn't do anything important anyway.