It's probably your ABS ECU. it's located behind the battery. to get to it, pull the battery, and then remove the black plastic cover which is behind the batt. you'll see 2 black boxes behind the cover a little bit towards the center of the car. one is the ignition ECU the other is for the ABS.
However, before you go out and buy a new one, check your ABS sensors. there's one at each front wheel and one on the rear diff. Take them out and clean them and see if that works. If not, go to aurora auto wrecking in Seattle and see if you can pick up an ABS ECU. New they're almost $500 canadian.
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