I can help you with this 'cause i recently had to change my ABS controller. The ABS controller and the ABS hydraulic pump are all one unit. This unit is located behind the air filter and in front of the master cylinder. You will be able to see the top of the pump but you wont be able to see the actual ABS controller 'cause its under the pump. To identify the unit, look for a cylinder-type shape that is screwed to what looks like a block and to the left of it you'll see a harness with a connecter that plugs into the block. You'll know what I'm talkin about when you take a look under the hood.
The downside is if you have to change the pump or the computer, you'll have to replace the whole unit.
Hope I helped!!
1998 Platinum ZJ 5.9 Limited
K&N FIPK / MOPAR ECU / Bilstein Shocks / H&R springs / Addco sway bars