ENGINE MANAGEMENT SYSTEM – V8 DESCRIPTION AND OPERATION 18-2-45 Control Solenoid and Check Valve A = Advance B = Retard C = Vent The VCC solenoid is a two wire, pulse width modulated, oil pressure control valve. The valve has four ports; 1 Input Supply Port, Engine Oil Pressure 2 Output Retard Port, to rear of piston/helical gear (retarded camshaft position) 3 Output Advance Port , to front of piston/helical gear (advanced camshaft position) 4 Vent released oil pressure. A check valve is positioned forward of the solenoid in the cylinder head oil gallery. The check valve maintains an oil supply in the VCC transmission and oil circuits after the engine is turned off. This prevents the possibility of piston movement (noise) within the VCC transmission system on the next engine start.