i have a 2005 mitubishi galant and when i turn the key the lights go out someone said its the etacs module and i have a new battery what can it be

Double check the battery connections. The factory ones tend to break right where the bolt goes thru them. Also if the clamps appear to be all the way compressed they might be to stretched and not getting tight enough on the battery terminals. Also check the negative connection to the frame and motor. The one on the frame tends to corrode. Might try cleaning and tightening them.