Have an 03 Buick Lesabre (uses the same ABS setup as a Bonny). Problem is both the abs and brake light come on when you start the car for a few seconds, then go off like they're supposed to, but immediately come back on. I checked the fuses and they are fine. I went to have it scanned by 2 separate shops that have the hardware to do it. Both scanners could not communicate to find any ABS codes. They could read engine and trans codes just fine. I checked the plug going to the ABS motor, and there is power going to a brown wire, but the thick red wire has none (tested key on engine off). Anyone have a wiring diagram for the ABS system? Any suggestions?

Hopefully someone can chime in here on the 'red' wire. The brown wire is probably a signal wire with .5V or less on it. Not sure if the red wire is suppose to be powered by a relay or a switch.

The ABS system usually does not throw a DTC that can be read.

Let'* see if anyone has any ideas here. I'll pull a few manuals out and see if there is anything I can see that might help.