For a view of the oil flow diagram, refer to the 1996 TURM Manual.
To obtain Third gear, the PCM receives input signals from the VS Sensor and the PT 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.
