abs and trac off light are on

Hi, I just put all new brake lines on a 1999 concorde lx 3.2 auto with traction controll, I found that the abs unit was leaking inbetween the motor and valve body, I went to a local junk yard and pulled a unit from a 99 300m. I got it in and the abs and trac off light are on, but if I pull the harness and put it on the old one they go off. Do I need to go get another one or is it possible that it will go off after I drive it, "its still on jack stands","like if the 300m had a bad wheel counter", or are the abs codes stored on the ecm or,...... any info would be great.
Thanks