1998 Volkswagen Passat ECM unit

Ok here we go ive purchesd this car from a friend in these conditions cause I got it cheap reasons it cant get smoged there is no reading no codes nothing when you try to hook it up to the computer ther was a abs light on but I replaced the control module unit from the brake system well that fixed that problem that light went out but ther is still no reading when I use my scan tool.I even took it too a smog shop again same thing, oh no theres a engine light on with a icon of a lighting bolt any questions, there is a fuse for ecm unit shoud I start from there?