[Fzz]

This vid is for a ZJ (I think) but this repair solved my ABS light:

 

[Fzz]

As has been said above, if you got another used control unit there's no guarantee that won't have the same fault - my WJ came with the fault light on when i bought her, and someone had already fitted a used unit (along with all new abs sensors to try and get rid of the fault light...) - the unit fitted obviously had knackered joints but I don't think they changed the spec of the abs ecu between 99 & 05 - hopefully someone can confirm.