Chevrolet Equinox Service Manual: Park - Engine Running (Gen 2/Hybrid) Automatic Transmission Unit

When the gear selector lever is in the Park (P) position,fluid is drawn into the pump through the transmission fluid filterassembly. Line pressure is then directed to the followingvalves:

Fluid Pressure Directed in Preparation for a Shift

Manual Valve

Mechanically controlled by the gear selector lever, themanual valve is in the Park (P) position and prevents line pressurefrom the pressure regulator valve from entering the reverse anddrive fluid circuits.

Actuator Feed Limit Valve

Line pressure is regulated through the valve into theactuator feed limit circuit. Actuator feed limit fluid passesthrough orifice #10 to a differential area to move the valveagainst actuator feed limit valve spring pressure. Actuator feedlimit fluid is routed to the pressure control solenoids, the shiftsolenoid, and to the #4 ball check valve.

TCC Regulated Apply Valve

Shift solenoid fluid is routed to the TCC regulated applyvalve and moves the valve against TCC regulated apply valve springforce.

Default Override Valve

Shift solenoid fluid is routed to the default override valveand moves the valve against default override valve springforce.

Low and Reverse Clutch Applies

R1/456 Pressure Control (PC) Solenoid

The R1/456 PC solenoid is energized (ON) allowing actuatorfeed limit fluid to enter the PCS R1/456 clutch fluid circuit. PCSR1/456 clutch fluid is then routed through orifice #11 to theR1/4-5-6 clutch regulator valve, and through orifice #34 to theR1/4-5-6 clutch boost valve.

R1/4-5-6 Clutch Regulator Valve

PCS R1/456 clutch fluid at the R1/4-5-6 clutch regulatorvalve, opposes R1/4-5-6 clutch regulator spring force and orificedR1/456 clutch feedback fluid pressure to regulate line pressureinto the R1/456 clutch feed circuit. R1/456 clutch feed fluid isrouted to the R1/4-5-6 clutch boost valve and to the clutch selectvalve.

R1/4-5-6 Clutch Boost Valve

PCS R1/456 clutch fluid pressure acts on a differential area,moving the R1/4-5-6 clutch boost valve against R1/4-5-6 clutchboost valve spring force, to regulate R1/456 clutch feed fluid intothe R1/456 clutch feedback circuit. As PCS R1/456 clutch fluidpressure is increased to a given value, the R1/4-5-6 clutch boostvalve opens the R1/456 clutch feedback circuit to exhaust backfill.This results in the R1/4-5-6 clutch regulator valve moving to thefull feed position, sending full R1/456 clutch feed pressure (fullline pressure) to the low and reverse clutch.

Shift Solenoid

The shift solenoid is energized (ON) allowing actuator feedlimit fluid to enter the shift solenoid circuit. Shift solenoidfluid is routed to the clutch select valve through orifice #13, tothe TCC regulated apply valve through orifice #14, and throughorifice #44 to the default override valve.

Clutch Select Valve

Shift solenoid fluid is routed to the clutch select valve andmoves the valve against clutch select valve spring force. Thisallows R1/456 clutch feed fluid to pass through the valve and enterthe R1 circuit. R1 fluid is then routed through orifice #42 to thelow and reverse clutch assembly in preparation for a shift into lowor reverse gear.

Low and Reverse Clutch

R1/456 fluid enters the transmission case assembly and movesthe low and reverse clutch piston against spring force to apply thelow and reverse clutch plates. In Park range, the low and reverseclutch has no effect. However, when Reverse or a forward range isselected, only one apply device has to be energized, which helpscreate a smooth starting motion.

Accumulator

PCS R1/456 clutch fluid is also routed to an accumulatorvalve. The accumulator valve is used to dampen any pressureirregularities occurring in the PCS R1/456 clutch fluid circuit.This helps to control clutch apply fluid pressure and clutch applyfeel.

Park – EngineRunning-–-Gen 2/Hybrid

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