2eye is probably right since he is an Isuzu mechanic/technician. If the problem is where he says it is, it sounds like the rear sensor on the differential may be the problem. Here's the link to the ABS codes
http://forums.klipsch.com/idealbb/files/ABS%20DTC.pdf
It should still work. Good Luck and let us know what you find and what you did to fix it.