It might look like this.
Clean the frame and the ring connector with a whizwheel, then reattach with a star washer. Use a new bolt to tighten if needed. Spray the area with rubber undercoating once everything is tightened down.
If this doesn't work, then you will need to get the actual code read. Not every OBDII scanner can read ABS codes; you will need one specifically marked as reading ABS codes.
(The government specifically restricted code readers from reading ABS codes until the last few years.)