alright, the ECU is your computers brain, tells you car what to do. It is located under the carpet on the passenger footwell, right up by the firewall. Check out Ami's (LadyNRedSi) website at
http://www.4thgenerationcivic.com for the ECU Codes. You just count the blinks and yes, there will be a pause in between if you have multiple codes. The LED will be red. awww yes, it does nothing when there is nothing wrong, just when the check Engine light is on is when you need to check it.