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. The torque converter clutch pulse width modulated (TCC PWM) solenoid (1) and the shift solenoids C (5), D (2), and E (3) are N/C. Both solenoid types have an orifice, electrical windings, an iron core, and a steel check ball.
The solenoids used in the 1000 Series differ in their ability to control flow or fluid pressure. The solenoids may operate in the open or closed state with no modulation capability, shift solenoids C, D, and E, an intermediate flow and resultant pressure based on duty cycle, torque converter clutch pulse width modulated (TCC PWM) solenoid, or produce pressure proportional to current (PPC), pressure control solenoid A and B.
Shift solenoids C, D, and E 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 C, D, and E. 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 pressure switch manifold, which provides feedback to the computer as to the position of the valve.
Modulated main pressure solenoid (7) is a normally closed 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 transmission control module (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 A (6) and B (4) are used to control on-coming, off-going, and holding pressure to the five clutches. These solenoids are referred to as PPC solenoids, since the output hydraulic pressure supplied by these solenoids is proportional to the controlled current command.