Hi i got an 1993 audi 90 Q CS

when i got it the antilock was off on the dash, i try to press the anti lock button on the dash and it wont turn on..... we plug the computer to see if its responding and didnt.. a faulty ABS relay? or the sensor it self?

thats my first problem its snow's alot in canada so quattro is awesome but without absit wouldnt have the same confort knowing that i can stop when i need it

My second problem is that my engine light turns on when i drive on the highway after 80km on a constant speed the check engine light would turn on it doesnt seem to affect my driving but i would like to know what was that light on for?

Any help or comments would be gladly accepted