When the shift lever is moved to the reverse (R) position from Park position, and the following changes occur in the transmissions hydraulic and electrical systems:

Manual Valve: Manual valve is in the Reverse position, then line pressure is sent to the reverse fluid circuits.

Reverse Lockout Valve: Reverse fluid flows to the reverse lockout fluid circuits through the reverse lockout valve.

Pressure Modulator Valve and Line Boost Valve: The reverse clutch fluid in the line boost valve increases line pressure to provide additional torque in Reverse. Throttle signal fluid pressure from PC Solenoid apply to line boost valve, and help to ensure the line pressure in Reverse according to throttle position and other TCM input signal.

#8 Ball Check Valve and Valve Bore #12: Seated in bottom channel plate, reverse lockout fluid goes against the #8 ball check valve to Low and Reverse clutch fluid passage, and flows into Low and Reverse clutch or reverse lockout fluid passage. Reverse lockout fluid pressure is throttled to control Low and Reverse clutch apply through valve bore #12.

Low and Reverse Clutch: Low and Reverse Clutch or Reverse lockout fluid pressure is sent to the outboard area of Low and Reverse Clutch piston, so the piston overcomes the spring tension to apply Low and Reverse Clutch Plate. Also, Reverse lockout fluid pressure is sent to the inside of Low and Reverse Clutch piston, and provide additional force to apply Low and Reverse Clutch Plate.

Important: Please remember the function of valve bore is to control fluid flow and the rate of clutch apply or release.

#1 Ball Check Valve: Seated in bottom channel plate, the reverse lockout fluid against #1 ball check valve and flows into Reverse clutch fluid passage through valve bore #13 of control valve body spacer plate.

Reverse Clutch: Reverse clutch fluid flows into reverse clutch housing, apply to reverse clutch piston and apply reverse clutch plate.

#2 Ball Check Valve: Seated in Bottom Channel Plate, reverse fluid goes to the #2 ball check valve to 2345 fluid passage and flows into 2345 or Reverse fluid passage.

TCC PWM - TCC Solenoid Valve: TCC PWM solenoid valve remains OFF. 2345 or Reverse fluid is restricted so it cannot flow into TCC signal fluid circuits. TCC PWM solenoid valve is de-energized under normal conditions. If TCC PWM solenoid valve is energized - while the vehicle is being driven in a forward gear and vehicle speed exceed a certain speed, if shift to Reverse at this time, TCC signal fluid will switch the reverse lockout valve to prevent the reverse fluid from flowing into reverse lockout fluid circuit and reverse clutch, and Low and Reverse Clutch will release to prevent damage to the transmission.