I have an 1999 Rodeo & the ABS light stays on (most of the time). I saw dane's posting & i have the same basic question, What triggers this light?
Btw, I had the unit replaced on a recall a few years back. There are no other problems except an ocasional brake vibration, but I understand how the system releases & the vibration is not a concern.

 

i have heard of lots of this problem with the various isuzu products...it must be a consistant issue with the ABS electronics