Transmission Solenoid - Operation

OPERATION

NOTE: A scan tool can only display a estimated pressure based on the current fed to the solenoid. Therefore if there's a stuck Line Pressure Regulating valve and the transmission has insufficient pressure, the scan tool will still display estimated MOD and Shift pressures because the solenoids are being fed the correct amount of current.

The solenoids are fed a 12-volt source from the TCM (Transmission Control Module). When an electrical current is applied to the solenoid coil, a magnetic field is created which produces an attraction to the plunger, causing the plunger to move and work against the spring pressure and the load applied by the fluid the valve is controlling. The plunger is normally directly attached to the valve which it is to operate. When the current is removed from the coil, the attraction is removed and the plunger will return to its original position due to spring pressure.

The plunger is made of a conductive material and accomplishes this movement by providing a path for the magnetic field to flow. By keeping the air gap between the plunger and the coil to the minimum necessary to allow free movement of the plunger, the magnetic field is maximized.

UPSHIFT/DOWNSHIFT SOLENOID VALVES










If a solenoid valve (1)(Figure 1) is actuated by the TCM, it opens and guides the control pressure (p-SV) to the assigned command valve. The solenoid valve remains actuated and therefore open until the shifting process is complete. The shift pressure (p-SV) to the command valve is reduced to zero as soon as the power supply to the solenoid valve is interrupted.

MODULATING PRESSURE CONTROL SOLENOID VALVE










The modulating pressure regulating solenoid valve (1)(Figure 2) assigns a proportional pressure to the current which is controlled by the TCM according to the load.

TORQUE CONVERTER LOCKUP CLUTCH PWM SOLENOID VALVE










The torque converter lockup PWM solenoid (1)(Figure 3) valve converts pulse-wave-modulated current controlled by the TCM into the appropriate hydraulic control pressure (p-S/TCC).

SHIFT PRESSURE CONTROL SOLENOID VALVE










The shift pressure regulating solenoid valve (1)(Figure 4) assigns a proportional pressure to the current which is controlled by the TCM according to the load.