Circuit Description
WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The system relay is energized when the ignition is ON. The system relay supplies voltage to the valve solenoids and the pump motor. This voltage is referred to as the system voltage. The EBCM microprocessor activates the valve solenoids by grounding the control circuit.