Manual Gear Shift
Manual Third Gear - TCC Applied
A manual 4-3 downshift is available to increase vehicle performance when the use of only three gear ratios is desired. Manual Third gear range also provides engine braking in Third gear when the throttle is released. A manual 4-3 downshift is accomplished by moving the selector lever into the Manual Third (D) position. This moves the manual valve and immediately downshifts the transmission into Third gear. Refer to Overdrive Range, 4-3 Downshift for a complete description of a 4-3 downshift. In Manual Third, the transmission is prevented, both hydraulically and electronically, from shifting into Fourth gear. The following information explains the additional changes during a manual 4-3 downshift as compared to a forced 4-3 downshift.
Manual Valve
The selector lever moves the manual shaft and manual valve into the Manual Third position (D). This allows line pressure to enter the D3 fluid circuit.
Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly
D3 fluid is routed to the TFP manual valve position switch and opens the normally closed D3 fluid pressure switch. The combination of the opened D3 switch and the closed D4 switch signals the PCM that the transmission is operating in Manual Third.
1-2 Shift Solenoid (SS) Valve
When Manual Third is selected, the PCM de-energizes the 1-2 SS valve to immediately downshift the transmission into Third gear. This electronically prevents Fourth gear.
3-4 Shift Valve
D3 fluid pressure assists spring force to keep the valve in the downshifted position against the signal fluid circuit. In this position, the valve blocks 3-4 signal fluid and the 4th signal fluid circuit is open to an exhaust port past the valve. Therefore, with D3 fluid pressure assisting spring force, Fourth gear is hydraulically prevented.
2-3 Shift Valve Train
With the 2-3 SS valve de-energized and open, actuator feed limit (AFL) fluid acting on the 2-3 shift valve holds both valves in the upshifted position. This allows D3 fluid to feed the overrun fluid circuit through the 2-3 shift valve.
Overrun Clutch Feed Checkball (#5)
Overrun fluid pressure seats the ball against the empty D2 fluid circuit.
Overrun Clutch Control Checkball (#6)
Overrun fluid pressure seats the #6 checkball and is orificed (#20) to fill the overrun clutch feed fluid circuit. This orifice controls the overrun clutch apply rate.
3-4 Relay Valve and 4-3 Sequence Valve
4th signal fluid pressure is exhausted from the end of the 3-4 relay valve. Overrun clutch feed fluid pressure assists spring force and closes both valves. This allows overrun clutch feed fluid to flow through the 4-3 sequence valve and fill the overrun clutch fluid circuit.
Overrun Clutch Piston
Overrun clutch fluid pressure moves the piston to apply the overrun clutch plates. The overrun clutch plates provide engine compression braking in Manual Third - Third Gear.
Overrun Clutch Air Bleed Checkball
This ball and capsule is located in the overrun clutch fluid circuit in the oil pump. It allows air to exhaust from the circuit as fluid pressure increases and also allows air into the circuit to displace the fluid when the clutch releases.
Torque Converter Clutch and Torque Converter Clutch PWM Solenoid Valve
The PCM de-energizes the TCC solenoid valve and operates the duty cycle of the TCC PWM solenoid valve to release the converter clutch prior to downshifting, (assuming the converter clutch is applied in Overdrive Range-Fourth Gear when Manual Third is selected). The PCM will re-apply the converter clutch in Manual Third-Third Gear when proper driving conditions have been met.
Pressure Control (PC) Solenoid Valve
The PC solenoid valve operates in the same manner as Overdrive Range, regulating in response to throttle position and other vehicle operating conditions.
Manual Third - First and Second Gears: Overrun Clutch Released
In Manual Third, the transmission upshifts and downshifts normally between First, Second and Third gears. However, in First and Second gears, the 2-3 55 valve is energized and the 2-3 shift valve train is in the downshifted position. The 2-3 shift valve blocks D3 fluid from entering the overrun fluid circuit and opens the overrun fluid circuit to an exhaust port at the valve.This prevents overrun clutch apply and engine compression braking in Manual Third-First and Second Gears.
Manual Second Gear
A manual 3-2 downshift can be accomplished by moving the gear selector lever into the Manual Second (2) position when the transmission is operating in third gear. This causes the transmission to shift immediately into second gear regardless of vehicle operating conditions. Also, the transmission is prevented from operating in any other gear, first, third or fourth. The following information explains the additional changes during a manual 3-2 downshift, as compared to a forced 3-2 downshift. Some vehicles in manual second gear will start out in first gear, while other vehicles will have a second gear start. Refer to the owners manual for specific applications.
Manual Valve
The selector lever moves the manual shaft and the manual valve into the manual second (2) position. This allows the line pressure to enter the D2 fluid circuit.
Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly
The D2 fluid is routed to the TFP manual valve position switch where it opens the normally closed D2 fluid pressure switch. With the D2 and the D3 pressure switches closed and the D4 pressure switch open, the TFP manual valve position switch signals the PCM that the transmission is operating in manual second.
Third and Fourth Gears Prevented
2-3 Shift Solenoid (SS) Valve
The PCM energizes the 2-3 SS valve and the AFL fluid pressure holds the 2-3 shift valve in the downshift position. This electronically prevents operation of the third and fourth gears.
2-3 Shift Valve Train
The D2 fluid is routed between the 2-3 shuttle and the 2-3 shift valves and causes the following:
- Regardless of the operating conditions, the D2 fluid pressure holds the 2-3 shift valve in the downshift position against the AFL fluid pressure.
- The 2nd fluid is blocked from entering the 3-4 signal fluid circuit and the 3-4 signal fluid circuit is open to an exhaust port at the valve.
- The 3-4 clutch cannot apply with the 3-4 signal fluid exhausted. Therefore, third and fourth gears are hydraulically prevented.
- The 2nd fluid feeds the servo feed fluid circuit, but the 2nd fluid circuit has no function in manual second.
- The AFL fluid is blocked by the 2-3 shift valve and the D432 fluid circuit is exhausted through the valve.
- The overrun fluid is exhausted through the 2-3 shuttle valve.
1-2 Shift Valve
The 1-2 SS valve is OFF, the signal A fluid exhausts through the solenoid and the spring force holds the valve in the upshifted position.
Overrun Clutch Remains Applied Overrun Clutch Feed Checkball (#5)
Orificed D2 fluid pressure seats the #5 checkball against the empty overrun clutch fluid circuit. This is done simultaneously with the overrun clutch fluid exhausting so that there is a continuous fluid supply to the overrun clutch feed fluid circuit.
Overrun Clutch Piston
A continuous supply of fluid pressure is routed to the piston in order to keep the overrun clutch plates applied.
Torque Converter Clutch
The converter clutch is released prior to downshifting into manual second-second gear. Under normal operating conditions the TCC will not apply in second gear.
Pressure Control (PC) Solenoid Valve
Important: Some vehicles in Manual Second Gear, at a stop, will start out in 1st gear, while others will have a second gear start. Refer to Vehicle Owners Manual.
The PCM output signal to the PC solenoid valve increases the operating range of torque signal fluid pressure in manual second. This provides the increased line pressure for the additional torque requirements during the engine compression braking and increased engine loads.
Manual First Gear
A manual 2-1 downshift can be accomplished by moving the gear selector lever into the manual first (1) position when the transmission is operating in second gear. The downshift to first gear is controlled electronically by the PCM. The PCM will not energize the 1-2 shift solenoid valve to initiate the downshift until the vehicle speed is below approximately 48 to 56 km/h (30 to 35 mph). Above this speed, the transmission operates in a manual first-second gear state. The following text explains the manual 2-1 downshift.
Manual Valve
The selector lever moves the manual shaft and the manual valve into the manual first (1) position. This allows the line pressure to enter the Lo fluid circuit.
Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly
Lo fluid is routed to the TFP manual valve position switch where it closes the normally open lo pressure switch. The addition of the 10 pressure switch being closed signals to the PCM that manual first is selected.
2-3 Shift Solenoid (SS) Valve
In both first and second gears, this solenoid is energized and maintains the signal B fluid pressure at the solenoid end of the 2-3 shift valve train.
2-3 Shift Valve Train
Held in the downshift position by the signal B fluid pressure from the solenoid, the valve train blocks the AFL fluid from entering the0432 fluid circuit. The D432 fluid circuit is open to exhaust past the valve.
1-2 Shift Solenoid (SS) Valve
Below approximately 48 to 56km/h (30 to 35 mph) the PCM energizes the normally open solenoid. This blocks the signal A fluid pressure from exhausting through the solenoid and creates the pressure in the signal A fluid circuit. Above this speed, the PCM keeps the solenoid de-energized and the transmission operates in manual first-second gear.
1-2 Shift Valve
Signal A fluid pressure moves the valve against the spring force and into the downshift position. In this position, Lo fluid from the manual valve is routed into the Lo/1st fluid circuit and D4 fluid is blocked from entering the 2nd fluid circuit. The 2nd fluid exhausts through an orifice and an annulus exhaust port past the valve. This orifice (#26) helps control the 2-4 band release during a 2-1 downshift.
2-4 Band Releases
2-4 Servo Assembly
The 2nd clutch fluid, which was fed by the 2nd fluid, exhausts from the servo. This allows the spring force from the servo cushion and the servo return springs to move the 2nd apply piston and apply the pin to release the 2-4 band. These spring forces help control the 2-4 band release.
1-2 Accumulator Assembly
The 2nd clutch fluid also exhausts from the 1-2 accumulator assembly. The spring force and the accumulator fluid pressure move the accumulator piston to assist the 2nd clutch fluid exhaust.
Accumulator Valve
As the accumulator fluid is filling the 1-2 accumulator assembly, the accumulator valve regulates the D4 fluid into the accumulator fluid circuit. This regulation, biased by torque signal fluid pressure and spring force, helps control the movement of the 1-2 accumulator piston. The 2nd clutch fluid exhaust, and the 2-4 band release.1-2 Upshift Checkball (#8)
Exhausting the 2nd clutch fluid pressure unseats the ball and is routed through the 2nd fluid circuit.
Lo and Reverse Clutch Applies
Lo Overrun Valve
The Lo/1st fluid is regulated through the 10 overrun valve and into the Lo/reverse fluid circuit in order to control the lo and reverse clutch apply.
Overrun Clutch Applied
The overrun clutch remains applied in manual first in order to provide engine compression braking.
Pressure Control (PC) Solenoid Valve
Similar to manual second, the PCM output signal to the PC solenoid valve increases the operating range of the torque signal fluid pressure. This provides the increased line pressure for the additional torque requirements during the engine compression braking and the increased engine loads.
3-2 Downshift Control Solenoid Valve and the 3-2 Control Valve
In first gear the solenoid is OFF, the AFL fluid is blocked by the solenoid,and the 3-2 signal fluid exhausts through the solenoid and the spring force opens the 3-2 control valve.