Sensor Continuity Check
WARNING: This page is about a different car, the 1988 Buick Riviera and 1988 Buick Reatta. However, it is still accessible from the selected car via links, so may be relevant.
Any condition that would result in a lack of continuity to the wheel speed sensor circuit would result in one of the above listed codes. Check for opens in circuits No. 884 and 885. Check for an open across sensor coil. A short to voltage on wheel speed sensor will also cause this type of failure.