Pressure Control Solenoid Valve

WARNING: This page is about a different car, the 2002 GMC Cab & Chassis Sierra and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The Pressure Control (PC) solenoid valve is attached to the valve body. The valve controls line pressure by moving a pressure regulator valve against spring pressure. The PC solenoid valve takes the place of the throttle valve or the vacuum modulator, which was used on past model transmissions.

The PCM varies line pressure based on engine load. Engine load is calculated from various inputs, especially the TP sensor switch. Line pressure is actually varied by changing the amperage applied to the PC solenoid valve from zero amps (high pressure) to 1.1 amps (low pressure). The PC solenoid valve current is periodically pulsed to prevent contamination from sticking the pressure regulator valve.

One diagnostic code is associated with the PC solenoid valve. DTC P0748 sets when the PCM detects a difference of 0.16 amp or more between the amperage commanded and actual amperage. While the DTC is set, the PC solenoid valve turns off. Recovery can occur after the next ignition cycle. DTC P0748 does not sense a hydraulic problem such as a stuck valve.