Vince, what makes you think it's your ECU is making a noise???? as they are in general solid state devices that make no noise at all!! as you do not wish to tell us what car you have it is impossible to give a considered answer but the clicking sound is most likely due to be a duff battery and the clicking is from the starter solenoid
nigel
August 2009
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.