i asked around and someone said the ABS module was bad

At first i was just doing a pad change on my wifes car. After i finished, the brakes were soft. So i then bled the brakes hoping thats what was wrong. There was some air in the lines and the brake firmed up but constant pressure the pedal would still drop slowly. So i asked around and someone said the ABS module was bad so I need to replace it Thanks - Cameron