Electronic Component Description: Solenoids
The 1000 Series control valve body contains both normally closed (N/C) and normally open (N/O) solenoids. A N/C solenoid remains closed until a signal from the TCM energizes the solenoid. A N/O solenoid remains open until the TCM energizes the solenoid. When a solenoid valve is in the closed position, the valve blocks the flow. When a solenoid valve is in the open position, flow is permitted through the valve. Shift solenoid 1 (SS1) (5), shift solenoid 2 (SS2) (2) and shift solenoid 3 (SS3) (3) are N/C. Both solenoid types have an orifice, electrical windings, an iron core, and a steel check ball.
Shift solenoids provide the necessary logic to distribute fluid to the correct clutches. The shift solenoids provide either full control main pressure or exhaust to the head of each of the corresponding shift valves. Since the valve states, stroked or unstroked, are critical to providing the correct transmission range, each shift valve has a pressure switch, located in the PSM, which provides feedback to the computer regarding the position of the valve.
Modulated main pressure solenoid (7) is a N/C solenoid used to modulate the transmission main pressure. Under specific conditions, such as low throttle setting, low engine torque, low engine speed, and low transmission output speeds, the TCM commands the solenoid ON. When the solenoid is applied, fluid is routed to the main pressure regulator valve; this in turn reduces the main pressure schedule and improves the volume of oil through the overage circuit. By modulating main pressure, the cooler flow at idle can be increased, allowing improved cooling and reducing transmission pump noise.
Pressure control solenoid 1 (PCS1) (6), pressure control solenoid 2 (PCS2) (4), and the torque converter clutch (TCC) (1) are used to control on-coming, off-going, and holding pressure to the 5 clutches and the TCC. These solenoids are referred to as variable bleed solenoids, since the output hydraulic pressure supplied by these solenoids is proportional to the controlled current command.