P0748 CHEVROLET - Pressure Control Solenoid Circuit Electrical
Low transmission fluid level
Dirty transmission fluid
Faulty Pressure Control Solenoid
Pressure Control Solenoid harness is open or shorted
Pressure Control Solenoid circuit poor electrical connection
When a transmission solenoid is malfunctioned, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is dirty, it's recommended to change the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a mechanical transmission failure and that the transmission will need to be rebuilt or replaced.
When is the code detected?
When the Powertrain Control Module (PCM) detects a continuous open or short in the Pressure Control (PC) solenoid valve circuit the P0748 code is set.
Engine Light ON (or Service Engine Soon Warning Light)
Transmission shift shock
P0748 Chevrolet Description
The Pressure Control (PC) solenoid valve is an electronic device that regulates transmission line pressure based on the current flow through its coil winding. The magnetic field produced by the coil moves the solenoid's internal valve which varies pressure to the pressure regulator valve. The Powertrain Control Module (PCM
) controls the PC solenoid valve by applying a varying amount of amperage to the solenoid. The applied amperage can vary from 0.1 to 1.1 amps. Low amperage (0.1 amp) indicates high line pressure. High amperage (1.1 amps) indicates low line pressure. The duty cycle of the PC solenoid valve is expressed as a percentage of energized ON time. Zero percent indicates zero ON time (non-energized) or no current flow. Approximately 60% at idle indicates maximum ON time (energized) or high current flow. The PCM
determines the appropriate line pressure for a given load by comparing the throttle position (TP) voltage, the engine speed and other inputs.