Valve Body: Description and Operation

VALVE BODY CONTROL FUNCTIONS

Valve Body Main Control Component Identification:

NOTE: The numbers in parenthesis correspond with the numbers in the Valve Body Main Control Component Identification image.

(1) The intermediate servo accumulator controls band capacity on 1-2 shift.
(2) The overdrive servo accumulator controls overdrive band capacity on 3-4 upshifts.
(3) The 3-4 back-out valve controls the rate at which overdrive servo release oil exhausts on 3-4 back-out shifts.
(4) The 3-2 high clutch release valve controls the rate at which high clutch oil exhausts on higher speed 3-2 downshifts.
(5) The 3-2 intermediate servo release valve controls the rate at which intermediate servo release oil exhausts on higher speed 3-2 downshifts.
(6) The 3-2 kickdown timing valve sends intermediate servo release and high clutch oil to the torque demand valve during 3-2 downshifts at lower speeds. At higher speed, this valve moves down and intermediate servo release and high clutch oil drains through the 3-2 intermediate servo release kickdown control and 3-2 high clutch kickdown control valves.
(7) The 3-2 coast control valve controls the rate at which intermediate servo release and high clutch oil exhaust on 3-2 coasting downshifts.
(8) The throttle pressure booster valve increases throttle pressure output for shift delay at lower engine manifold vacuum levels.
(9) The 1-2 transition valve, along with the 2-3 back-out valve, will prevent an intermediate to reverse band tie-up on a manual 1-2 shift.
(10) The 2-3 back-out valve prevents tie-up if driver backs off accelerator during 2-3 upshift.
(11) The engagement control valve feeds the forward clutch through a small orifice at low Throttle Valve (TV) pressures, or through a larger orifice at higher TV pressures.
(12) The torque demand control valve controls the rate at which high clutch and intermediate servo release oil exhausts at lower speed 3-2 downshifts.
(13) The cut back valve reduces control pressure as road speed increases.
(14) The oil pressure regulator valve regulates main control pressure.
(15) The main oil pressure booster valve increases or decreases main control pressure in relation to throttle pressure, and provides higher line pressure in reverse.
(16) The throttle downshift valve reroutes line pressure to override the normal automatic upshift schedule and provide forced downshifts.
(17) The manual control valve moves with shift selector and directs control pressure to various passages to provide automatic function.
(18) The 2-Low range coasting boost valve boosts pressure in selector positions 1 and 2 at closed or nearly closed throttle.
(19) The 1-2 shift valve controls upshift from 1st to second and downshift from 2nd to 1st.
(20) The D2 shift valve is used in combination with the 1-2 shift valve to provide a 2nd gear start in 2 range.
(21) The 2-3 shift valve controls upshift from 2nd to high and downshift from high to 2nd.
(22) The 2-3 throttle pressure modulator valve provides a modulated pressure to the 2-3 shift valve at higher TV pressures. This modulated pressure helps to delay 2-3 shifts at higher TV pressures.
(23) The 4-3 torque demand valve routes high clutch oil to the 3-4 shift valve at lower vacuums. This provides for a higher road speed 4-3 torque demands at lower vacuum.
(24) The converter clutch shift valve, along with the converter clutch shuttle valve and solenoid, controls converter clutch engagements and disengagements.
(25) The converter clutch throttle pressure modulator valve sends a modulated pressure to the converter clutch shift valve at higher TV pressures. This modulated pressure helps to delay converter clutch upshifts at higher TV pressures.
(26) The 3-4 shift valve controls the scheduling for 3-4 upshifts and 4-3 downshifts.
(27) The 3-4 throttle pressure modulator valve provides a modulated pressure on the 3-4 shift valve at high TV pressures. This modulated pressure helps to delay 3-4 upshifts at higher TV pressures.
(28) The converter clutch shuttle valve, when bottomed against the plug, directs flow so the converter clutch will be disengaged. When the valve compresses the spring, flow is directed so the converter clutch engages. The solenoid also controls the position of this valve.