WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
DTC C0201 (Under 8600 GVW)
Circuit
Short to Ground
Open/High Resistance
Short to Voltage
Signal Performance
Antilock Brake System (ABS) Enable Relay Contact Circuit