ABS Light on. What to check?

I just replaced both front pads calipers and rubber hoses. I have a 91 Corsica with 94k and 3.1 engine. What the car does now with hard braking is that the drivers front locks up. ABS light was on before the new items and still on now. Does the sensor need cleaned? I haven't checked the rear brakes yet (drum..ewww). How is the system set up? Fronts on one part of the system and rear on the other or driver front and passenger rear on one and passenger front and driver rear? I'm getting tired of running red lights because of the locking wheel and sure don't want a ticket either!!

Codes?

Yeah split diagonal system.

Probably got one side of the system still has air in it.

Check ABS sensors for damage, dirt or improper air gap...and inspect their wiring...

How do I get codes from the ABS system? Do I needThanks for the info on the system setup. I'll check the air gap and clean if necessary when the weather drys out some.

Sorry about that. I didn't finish my question. Do I need any special tools to get the ABS codes? Thanks.