Park or Neutral - Engine Running (Park - Without Driver Shift Control) through Shift Accumulation
Description and OperationPark or Neutral - Engine Running (Park - Without Driver Shift Control)
When the gear selector lever is in the Park (P) position and the engine is running, fluid is drawn into the oil pump. Line pressure is directed to the pressure regulator valve.
Pressure Regulation
Pressure Regulator Valve
The pressure regulator valve regulates the pump output (line pressure) in response to a torque signal fluid pressure, which acts on the boost valve, the spring force, and the line pressure acting on the end of the valve. Line pressure is directed to the manual valve, to both accumulator valves, to the torque signal regulator valve, to the TCC regulated apply valve, to the temperature sensor in the Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.), and to the actuator feed limit valve. Also, line pressure feeds the converter feed fluid circuit through the pressure regulator valve.
Actuator Feed Limit (AFL) Valve
Line pressure is routed through the valve and into the actuator feed fluid circuit. The valve limits the actuator feed fluid pressure to a maximum pressure. Actuator feed fluid is routed to the pressure control solenoid and to each of the shift valves. The fluid also feeds the 1-2 signal and the 2-3 signal fluid circuits.
Pressure Control Solenoid (PCS) Valve
Controlled by the PCM, the PCS valve regulates the filtered actuator feed fluid pressure which acts on the end of the torque signal regulating valve.
Torque Signal Regulating Valve
Important: Actuator feed fluid continues to feed the 2-3 signal fluid circuit through orifice #6. However, the exhaust port through the 2-3 shift solenoid valve is larger that orifice #6 in order to prevent a pressure increase in the 2-3 signal fluid circuit.
The torque signal regulating valve regulates the line pressure into the torque signal fluid circuit. Filtered actuator feed fluid pressure from the PCS controls this regulation. torque signal fluid pressure is routed to the accumulator valves and to the boost valve in order to control shift feel.
Low and Reverse Band Applies
Manual Valve
The gear selector lever mechanically controls the manual valve, which is in Park (P) position. The manual valve directs line pressure into the PRND4 and the PRN fluid circuits.
Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
PRND4 fluid is routed to the PRND4 fluid pressure switch in the TFP Val. Position Sw. Assembly, which signals the PCM that the transmission is in the Park (P) position. Line pressure is routed to the A/T Fluid Temperature Sensor in the TFP Val. Position Sw. Assembly.
1-2 Shift Solenoid Valve
Energized by the PCM, the normally open 1-2 shift solenoid valve is On and blocks the 1-2 signal fluid from exhausting. The 1-2 signal fluid pressure acts on the 1-2 and the 3-4 shift valves.
1-2 Shift Valve
The 1-2 signal fluid pressure holds the valve in the downshifted position against a spring force Low/PAN fluid is routed through the 1-2 shift valve and into the Low band fluid circuit.
Low and Reverse Servo
Low band fluid is routed to the inner area of the servo piston. Low band fluid pressure moves the servo piston and pin assembly against a spring force in order to apply the low/reverse band.
2-3 Shift Solenoid Valve
The normally open 2-3 shift solenoid is Off and the 2-3 signal fluid is exhausted through the solenoid.
2-3 Shift Valve
A spring force holds the 2-3 shift valve in the downshifted position.
3-4 Shift Valve
The 1-2 signal fluid pressure holds the 3-4 shift valve against a spring force in the First and the Fourth gear positions.
Lube 2
The lube 2 fluid circuit is fed by line pressure at the pressure regulator valve. Lube 2 fluid is routed through the oil feed pipes and into the forward clutch support. Lube 2 fluid provides lubrication in the rear of the transmission.
Shift Accumulation
1-2/3-4 Accumulator Valves
Line pressure is regulated into accumulator fluid pressure. Torque signal fluid pressure acting on the end of the valve basically controls this regulation.
1-2, and 3-4 Accumulator Assemblies
Accumulator fluid is routed to each of the accumulator assemblies in preparation for upshifts. The fluid which is routed to the 1-2 and to the 3-4 accumulators is orificed by the #4 and the #7 checkballs. The 2-3 accumulator fluid circuit does not use a checkball in order to orifice accumulator fluid to the 2-3 accumulator.
Torque Converter/Cooler and Lube Circuits
Refer to Reverse range for a complete description of these circuits.
Park - Engine Running - Without Driver Shift Control
Park or Neutral - Engine Running (Neutral- Without Driver Shift Control)
When you move the gear selector lever from the Reverse position to the Neutral position, the following changes occur to the hydraulic and electrical systems.
Reverse Clutch Releases
Manual Valve
The manual valve is moved to the Neutral position, where the valve blocks the line pressure from entering the Reverse fluid circuit. The reverse fluid circuit is opened to an exhaust at the manual valve.
Reverse Clutch
Reverse fluid exhausts from the reverse clutch and the clutch releases. This action shifts the transmission in to Neutral position. Boost Valve
Reverse fluid exhausts from the boost valve and line pressure regulation returns to the normal operating range.
A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
Reverse fluid pressure exhausts from the TFP Val. Position Sw. Assembly. This action signals the PCM that the transmission is either in Neutral (N) or Park (P) position.
Low and Reverse Band Remains Applied
Important: In Park, Reverse, and Neutral positions the shift solenoid valves are shown to be in the First gear state. this is the normal operating state when the vehicle is stationary or at low vehicle speeds. However, the PCM will change the shift solenoid valve states depending on the speed of the vehicle. For example, if the Neutral range is selected when the vehicle is operating in Second gear, the shift solenoid valves will remain in a Second gear state. But with the manual valve in Neutral, line pressure is blocked, drive fluid exhausts and the transmission will shift into Neutral.
1-2 Shift Solenoid Valve
As in Park and Reverse positions, the solenoid valve is energized and 1-2 signal fluid pressure acts on the 1-2 shift valve.
1-2 Shift Valve
The 1-2 signal fluid pressure keeps the 1-2 shift valve in the downshifted position. Low/PAN fluid continues to feed the low band fluid circuit.
Low and Reverse Servo
Reverse fluid exhausts from the servo. However, low band fluid pressure continues to act on the inner area of the servo piston in order to keep the band applied.
Neutral - Engine Running - Without Driver Shift Control Reverse (Without Driver Shift Control)
Important: The explanation of each gear range is primarily limited to those changes from the previous range. However, some component descriptions are repeated for clarity and continuity.
When you move the gear selector lever to the Reverse (R) position (from the Park position), the following changes occur in the transmission's hydraulic and electrical systems.
Pressure Regulation
Manual Valve
With the manual valve in the reverse position, line pressure is directed into the reverse fluid circuit, in addition to the PRND4 and the PRN fluid circuits, which were used in Park position.
Pressure Regulator and Boost Valves
Reverse fluid is routed to the boost valve. Reverse fluid assists torque signal fluid pressure. The addition of reverse fluid pressure increases the operating range of the line pressure in Reverse position.
A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
Reverse fluid is routed through the 1-2 shift valve and to the TFP Val. Position Sw. Assembly, which signals the PCM that the transmission is in Reverse position.
Reverse Clutch Applies
Reverse Clutch
Reverse clutch fluid pressure applies the reverse clutch.
Low and Reverse Band Remains Applied
1-2 Shift Solenoid Valve
The PCM keeps the solenoid valve energized in Reverse position. The 1-2 signal fluid pressure acts on the 1-2 shift valve.
1-2 Shift Valve
he 1-2 signal fluid pressure keeps the 1-2 shift valve in the downshifted position. Low/PAN fluid continues to feed the low band fluid circuit.
Low and Reverse Servo
Reverse fluid is routed to the outer area of the servo in order to increase the servo apply pressure in the Reverse position.
Torque Converter Clutch
Pressure Regulator (PR) Valve
Line pressure is routed through the PR valve and into the converter feed fluid circuit. Converter feed fluid is routed to the TCC feed limit valve.
TCC Feed Limit Valve
Converter feed fluid is routed through the valve and into the TCC feed limit fluid circuit.
TCC Regulated Apply Valve
A spring force holds the valve in the release position, thereby blocking line pressure.
TCC Control Valve
A spring force holds the valve in the release position. TCC feed limit fluid is routed into the release fluid circuit. Fluid returns from the converter in the apply fluid circuit. This fluid is routed through the valve and into the cooler fluid circuit.
Torque Converter
Release fluid pressure is routed to the torque converter in order to keep the TCC released. Fluid leaves the converter in the apply fluid circuit.
Cooler and Lube
Lube 1
Cooler fluid is routed through the transmission oil cooler, which is located in the vehicle radiator, and into the lube 1 fluid circuit. Lube 1 fluid is routed through the input shaft in order to lubricate the transmission components in the front of the transmission.
Lube 2
The lube 2 fluid circuit is fed by line pressure at the pressure regulator valve. Lube 2 fluid is routed through the oil feed pipes and into the forward clutch support. Lube 2 fluid provides lubrication in the rear of the transmission. The lube 2 fluid circuit is fed by line pressure at the pressure regulator valve. Lube 2 fluid is routed through the oil feed pipes and into the forward clutch support. Lube 2 fluid provides lubrication in the rear of the transmission.
Reverse - Without Driver Shift Control
Overdrive Range, First Gear (Without Driver Shift Control)
When you move the gear selector lever to the Overdrive (D) position from the Neutral (N) position, the following changes occur in order to shift the transmission into Overdrive Range-First Gear.
Manual Valve
In the Overdrive position, the manual valve directs line pressure into the drive fluid circuit. The manual valve blocks line pressure from entering the PRN fluid circuit and the manual valve opens the PRN fluid circuit in order to exhaust.
Low and Reverse Band Releases
Low and Reverse Servo
Low band fluid pressure exhausts from the servo, releasing the servo and the low and reverse band.
Forward Clutch Applies
Forward Clutch
Drive fluid is orificed into the forward clutch fluid circuit. Forward clutch fluid pressure applies the forward clutch.
1-2 Shift Solenoid Valve
In first gear, the PCM energizes the 1-2 shift solenoid valve and the 1-2 signal fluid pressure acts on the 1-2 shift valve.
1-2 Shift Valve
The 1-2 signal fluid pressure keeps the 1-2 shift valve in the downshifted position against a spring force. Drive fluid is routed through the 1-2 shift valve.
A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
Drive fluid is routed to the TFP Val. Position Sw. Assembly, which signals the PCM that the transmission is in the Overdrive range.
Overdrive Range, First Gear - Without Driver Shift Control
Overdrive Range, Second Gear (Without Driver Shift Control)
As vehicle speed increases and operating conditions become appropriate, the PCM de-energizes the 1-2 shift solenoid valve in order to shift the transmission into Second gear. The manual valve remains in the Overdrive (D) position and line pressure is routed into the drive and PRND4 fluid circuits.
Second Clutch Applied
1-2 Shift Solenoid Valve
The normally open shift solenoid valve is de-energized and 1-2 signal fluid exhausts through the open valve.
1-2 Shift Valve
Important: Filtered actuator feed fluid continues to feed the 1-2 signal fluid circuit through orifice #7. However, the exhaust port through the solenoid is larger than orifice #7 in order to prevent a pressure increase in the 1-2 signal fluid circuit.
With 1-2 signal fluid pressure exhausted, a spring force moves the valve into the upshifted position. Drive fluid is routed into the 2-3 drive fluid circuit. Drive fluid also continues to flow through the valve and to the A/T Fluid Pressure Manual Valve Position Switch.
#2 Checkball (Second Clutch Apply)
The 2-3 drive fluid seats the #2 checkball, forcing the 2-3 drive fluid through the #3 orifice and feeding the second clutch fluid circuit. the #3 and the #4 orifices help to control the apply feel of the second clutch.
Second Clutch
The second clutch fluid pressure applies the second clutch, which shifts the transmission into Second gear.
Shift Accumulation
1-2 Accumulator
Second clutch fluid is also routed to the 1-2 accumulator piston. A combination of second clutch fluid pressure and the 1-2 assist spring force moves the piston against this spring force and the 1-2 accumulator feed fluid pressure. This action absorbs the initial second clutch fluid pressure in order to cushion the second clutch apply. The movement of the 1-2 accumulator piston forces some of the fluid out of the accumulator.
1-2 Accumulator Valve
The 1-2 accumulator feed fluid which is forced from the 1-2 accumulator unseats the #4 checkball. This fluid is then routed back to the 1-2 accumulator valve. This pressure forces the 1-2 accumulator valve against a combination of spring force and torque signal fluid pressure in order to regulate the exhaust of excess accumulator fluid. This regulation provides additional control for the second clutch apply.
TCC Control - Pulse Width Modulated (PWM) Solenoid Valve
Filtered 2-3 drive fluid is routed to the TCC control solenoid valve. Under normal operating conditions the TCC control solenoid valve is Off in Second gear. This valve blocks filtered 2-3 drive fluid from entering the TCC signal fluid circuit.
Torque Converter Clutch
With the TCC control solenoid valve Off, the converter clutch is released in Second gear.
2-3 Shift Solenoid Valve
The 2-3 shift solenoid valve remains Off in Second gear, and the 2-3 signal fluid exhausts through the normally open solenoid valve.
2-3 Shift Valve
A spring force keeps the 2-3 shift valve in the downshifted position. In this position the valve blocks 2-3 drive fluid, in preparation for the upshift into Third gear.