Park - Engine Running

Park - Engine Running:

PARK - (Engine Running)

When the gear selector lever is in the Park (P) position and the engine is running, fluid is drawn into the scavenger pump from the bottom pan and routed into the side cover. From the side cover fluid is drawn through the main filter into the primary and secondary oil pump assemblies. Line pressures from the primary and secondary oil pump assemblies are then directed to the following control devices:

PRESSURE REGULATION

Pressure Regulator Valve: Regulates pump output in response to torque signal fluid pressure, reverse, orificed line pressure and spring force. Line pressure from the pressure regulator valve is then routed to the actuator feed limit valve, the 1-2 & 3-4 accumulator valve, the 2-3 accumulator valve, and the converter clutch regulating valve.

Actuator Feed Limit Valve: Line pressure is routed to the valve and limited to a maximum pressure as it passes through the valve and enters the actuator feed circuit. Actuator feed is then routed to the pressure control solenoid, and into the solenoid "A" and "B" fluid circuits.

SHIFT ACCUMULATION

1-2 & 3-4 Accumulator Valve: Biased by torque signal, 3rd clutch and orificed primary accumulator pressures, it regulates primary accumulator pressure. Primary accumulator is routed to the spring side of the forward accumulator piston, checkball #2, and to checkball #3.

#2 Checkball (Primary Accum/1-2 Accum.): Located in the accumulator housing, it is seated against the spacer plate to route primary accumulator fluid through orifice #14 and to the spring side of the 1-2 accumulator piston.

#3 Checkball (Primary Accum, 3-4 Accum.): Located in the accumulator housing, it is seated against the spacer plate to route primary accumulator fluid through orifice #13 and to the spring side of the 3-4 accumulator piston.

2-3 Accumulator Valve: Biased by torque signal and orificed secondary 2-3 accumulator pressures and spring force, it regulates 2-3 accumulator circuit pressures. Line pressure at the valve feeds into the secondary 2-3 accumulator circuit and is then routed to checkball #10.

#10 Checkball (2-3 Accumulator): Located in the case cover, it is seated against the spacer plate to route secondary 2-3 accumulator fluid through orifice #32 and into the 2-3 accumulator circuit. 2-3 accumulator fluid is then routed to orifice #32 and the spring side of the 2-3 accumulator piston.

HYDRAULIC CONTROLS

Manual Valve: Mechanically controlled through the gear selector lever, it directs line pressure (from the pressure regulator valve) to the pressure switches and also into the PRN, PRND4 and PRND43 circuits.

Pressure Switch: A device containing five hydraulically activated (normally open) pressure switches which are monitored by the Powertrain Control Module (PCM). The switches close or open electrical circuits when hydraulic fluid acts on the diaphragm inside the switches to provide information to the PCM regarding the position of the manual valve. In Park, the PRND4 and PRND43 switches are closed thereby completing their electrical circuits.

Force Motor Feed Filter: Located in the valve body, it filters actuator feed fluid before it is routed to the pressure control solenoid.

Pressure Control Solenoid: Controlled by the PCM, it regulates filtered actuator feed pressure entering the torque signal circuit. Torque signal fluid is then routed to the pressure regulator valve, the 1-2 & 3-4 accumulator valve, and the 2-3 accumulator valve.

Shift Solenoid "B": De-energized (OFF) by the PCM allowing fluid in the solenoid "B" circuit to exhaust. Filtered actuator feed that enters the solenoid "B" circuit through orifice #16 will exhaust through the solenoid.

Shift Solenoid "A": Energized (ON) by the PCM, it blocks the exhaust port through the solenoid thereby creating high pressure in the solenoid "A" circuit. Solenoid "A" pressure holds the 1-2 shift valve in the downshifted position and is also routed to the 3-4 shift valve.

1-2 Shift Valve: Held in the downshifted position by high solenoid "A" pressure, PRN fluid passes between two valve lands and enters the lo/reverse band apply fluid passage.

3-4 Shift Valve: Solenoid "A" fluid routed to the end of the valve moves the valve against spring force and holds it in upshifted position.

#6 Checkball (Lo & Reverse Band Apply/Reduce): Located in the valve body, it seats against the lo & reverse band reduce passage and routes fluid to the lo & reverse servo piston.

TORQUE CONVERTER/COOLER AND LUBE

(See "Reverse" gear range)