Hey all you geniuses!

I have been to two different dealerships with this problem, spent a lot of money with no success. The Advancetrac light has been on full time for a couple of months now, and the system obviously not functioning. Initial codes read u1901 and u2526 (i think)--send and receive error from the ABS Module. I replaced the module with a used one; the codes were rectified but the light stayed on. Subsequently they have tried replacing the instrument cluster, traced all the wiring and a bunch of other time consuming (read, expensive) fixes to no avail. They say without a code to follow it's hard to know what to try next. Anybody have experience with this problem?

Thanks!