To obtain Third gear, the PCM receives input signals from the VS Sensor and the TP Sensor in order to de-energize (turn OFF) the current supply to the 2-3 shift solenoid valve (315). This allows the 2-3 shift solenoid valve fluid to exhaust. When this occurs, a spring force moves the 4-3 manual downshift valve (360). Line pressure at the end of the 2-3 shift valve (357) moves the 3-2 manual downshift valve (356) against a spring pressure. Line pressure also at the manual 3-2 downshift valve (356) enters the 2-3 shift solenoid valve OFF passage. This pressure helps to prevent the 1-2 shift valve (318) from moving. When the 2-3 shift valve (357) moves, D-4 fluid enters the third fluid passage. The third fluid passage feeds fluid to the following:
| • | The converter clutch solenoid (315), where the fluid exhausts through the solenoid |
| • | The 1-2 shift valve (318) |
| • | The #9 checkball (372). Fluid seats the checkball, forcing the fluid through an orifice and into the third clutch passage. |
The third clutch passage directs the fluid to seat the #4 checkball (372), sending the fluid into the third clutch/Lo-First passage in order to apply the third clutch. Third clutch fluid pressure is also sent to the 2-3 accumulator piston (136). This forces the piston against both the spring and the 2-3 accumulator fluid in order to cushion the third clutch application. The 2-3 accumulator fluid is then forced to exhaust at the 2-3 accumulator valve (343). In Third gear, the input clutch is released, allowing input clutch application fluid to exhaust through the 3-4 shift valve (362) into the input clutch feed passage. At the 2-3 shift valve (357), exhausting input clutch application fluid is directed into the D-3 passage and out of the manual valve (404).
2-3 Shift Solenoid Valve (315)
The 2-3 shift solenoid valve de-energizes, allowing the 2-3 shift solenoid valve fluid to exhaust through the solenoid. Spring pressure forces the 4-3 manual downshift valve (360) to move, while line pressure moves the 2-3 shift valve (357) and the 3-2 manual downshift valve (356).
#9 Checkball (372)
The #9 checkball is located in the valve body (300). The checkball forces third clutch fluid through a feed orifice and into third clutch passage.
#4 Checkball (372)
The #4 checkball is located in the channel plate (400). The checkball directs third clutch fluid into the third clutch/Lo-First passage in order to apply the third clutch.
2-3 Shift Valve (357)
When shifted, the 2-3 shift valve allows D-4 fluid to enter the third passage in order to perform the following tasks:
| • | Stroke the 2-3 accumulator piston (136) |
| • | Apply the third clutch |
| • | Direct fluid to the converter clutch solenoid (315) |
The 2-3 shift valve also allows the input clutch application fluid to exhaust into the D-3 passage and out at the manual valve (404).
2-3 Accumulator Piston (136)
The 2-3 accumulator piston cushions the application of the third clutch by using third clutch fluid to force the piston against a spring force and against the 2-3 accumulator fluid.
2-3 Accumulator Valve (343)
The 2-3 accumulator valve regulates the exhaust of the 2-3 accumulator fluid during third clutch application.
Overdrive Range, Third Gear - TCC Not Applied
