Chevrolet Equinox Service Manual: Drive Range, First Gear Engine Braking Automatic Transmission Unit

When the gear selector lever is moved to the Drive-(D) range from the Neutral-(N)position, the transmission will provide engine braking. In this operating range, thenormally-low 1234-pressure control solenoid-5 is commanded ON and in the engine brakingmode the following changes occur within the hydraulic circuits:

Fluid Pressure is Directed to the 1-2-3-4 Clutch and the Low & Reverse Clutch to ProvideEngine Braking

Manual Valve

The manual valve is moved to the Drive-(D) position and allows line fluid pressureto enter the drive fluid circuit. Drive fluid is then routed to the clutch selectvalve-2.

Clutch Select Valve 2

Drive fluid at the clutch select valve-2 passes through the valve and enters the drivebrake circuit. Drive brake fluid is then routed to the clutch select valve-3.

Clutch Select Valve 3

Drive brake fluid at the clutch select valve-3 passes through the valve and entersthe Drive B fluid circuit. Drive B fluid is then routed to #1-ball check valve.

#1 Ball Check Valve

Drive B fluid seats the #1-ball check valve against drive-1-6 fluid to force drive-Bfluid into the 26/1234 feed passage. The 26/ 1234 feed fluid is routed through orifice-#31and, to the 2-6-clutch regulator valve. The 26/1234 feed fluid passes through the2-6-clutch regulator valve and enters the pressure switch-3-(PS3) fluid circuit. PS3fluid is then routed to the normally closedpressure switch-3 and opens the switch.

#6 Ball Check Valve

26/1234 feed fluid unseats the #6-ball check valve allowing 26/1234 feed fluid toenter the 1234 clutch feed circuit. The 1234-clutch feed fluid is routed through orifice-#25and then to the 1-2-3-4-clutch regulator valve.

1-2-3-4 Clutch Applies

1234 Pressure Control Solenoid 5

The 1234 pressure control solenoid-5 is commanded ON allowing actuator feed limitto enter the PCS-1234 clutch fluid circuit. PCS-1234 clutch fluid is then routed throughtorifice- #27 to the 1-2-3-4-clutch regulator valve. PCS1234-clutch fluid is also routedthrough orifice-#29 and then to the 1-2-3-4-clutch boost valve.

1-2-3-4 Clutch Regulator Valve

PCS1234-clutch fluid moves the 1-2-3-4-clutch regulator valve against 1-2-3-4-clutchregulator valve spring force to allow 1234-clutch feed fluid to pass through the valveand enter the 1234-clutch fluid circuit. The 1234-clutch fluid is then routed to the1234-clutch boost valve and the 1-2-3-4-clutch.

1-2-3-4 Clutch Boost Valve

PCS1234-clutch fluid pressure acts on a differential area moving the 1234-clutch boostvalve against the 1234-clutch boost valve spring. The 1234-clutch fluid passes throughthe valve and enters the 1234- clutch feedback circuit. As PCS 1234-clutch fluid pressureis increased to a given value, the 1234-clutch boost valve opens the 1234-clutch feedbackcircuit to exhaust. This resultsin the 1234-clutch regulator valve moving to the full feed position sending full 26-CL/1234CL feed pressure (full line pressure) to the clutch.

1-2-3-4 Clutch

The 1234-clutch fluid enters the 1234-clutch to move the piston against spring forceto apply the 1-2-3-4-clutch plates.

Drive Range, First Gear Engine Braking

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