You pull the negative terminal off of the battery for about 30 minutes, then turn the key to make sure all the residual power gets drained from the system....then hook er back up! Voila....clean ecu. I read somewhere after clearing the ecu to do this:
1. Start the truck and let it warm up without touching the gas. Turn it off
2. Start it again and let it settle into regular idle without touching the gas. Turn it off
3. Start it and go on an easy ride around the block. Turn it off
4. Start it and have a blast. Turn off when desired.
Not sure why or where it comes from...any help?
Just to add to this for everyone that's asking, you can speed this process up by holding the brake pedal for 15 or so seconds after you disconnect the battery, it will drain off the remaining charge faster. Then wait just about 5 minutes or 10 or 15 if you want to be conservative and reconnect. Not sure about the other parts that you mentioned Timmy, I've never heard that.
EDIT: Oh and I think the key has to be in the on position for the brake light to work...