Transmission Solenoid Valves

The 8L45/90 transmission contains a total of nine individual solenoids installed in various bore locations on the lower control valve body assembly. Seven of the nine solenoid valves are used to control pressure regulation and direction of transmission fluid and the two ON/OFF solenoid valves are only used to direct transmission fluid.

There are three slightly different variations of the pressure regulating solenoid valves used on this transmission. They are; high pressure normally low, high pressure normally high and low pressure normally high, variable force solenoid valves.

• High Pressure = Indicates the solenoid valve is controlling or directing line pressure.
• Low Pressure = Indicates the solenoid valve is directing a pressurized fluid that is less than line pressure.
• Normally Low = When no current is applied to the solenoid valve coil the variable restriction is closed, resulting in no or low pressure.
• Normally High = When no current is applied to the solenoid valve coil the variable restriction is open, resulting in maximum or high pressure.
• Variable Force Solenoid Valve = This type of solenoid can increase or decrease the amount of pressurized fluid based on the amount of current applied to solenoid valve coil.