ENGINE MANAGEMENT SYSTEM – V, DESCRIPTION AND OPERATION, VCC System. VCC Transmission and Sprockets The primary and secondary timing chain sprockets are integrated with the self-contained VCC transmission. The controlled adjustment of the camshaft occurs inside the transmission. Controlled oil pressure moves the piston axially. The helical gear cut of the piston acts on the helical gears on the inside surface of the transmission and rotates the camshaft to the specific advanced or retarded angle position. Three electrical pin contacts are located on the front surface to verify the default maximum retard position using an ohmmeter. This is required during assembly and adjustment.