Power Flows
Operation of the transmission is controlled by the Transmission Control Module (TCM), which electrically activates various solenoids to control the transmission gear selection.
The sequence of solenoid activation is based on programmed information in the TCM memory and physical transmission operating conditions such as:
- Vehicle speed
- Throttle position
- Engine load
- Transmission Control Switch (TCS) position.
All gear shifts from 1st to 8th and 8th to 1st are known as 'overlap' shifts. Overlap shifts are during a gear shift one clutch must remain capable of transmitting torque at a reduced main pressure until the other clutch is ready to accept the torque.
Engine torque is transferred, via operation of single or combinations of clutches to the 4 planetary gear trains. All gear trains are controlled by reactionary inputs from brake clutches to produce the eight forward gears and one reverse gear. The ratios are as follows:
| GEAR | 1ST | 2ND | 3RD | 4TH | 5TH | 6TH | 7TH | 8TH | REVERSE |
|---|---|---|---|---|---|---|---|---|---|
| Ratio | 4.714 | 3.143 | 2.106 | 1.667 | 1.285 | 1.000 | 0.839 | 0.667 | 3.317 |
Shift Elements
| ITEM | DESCRIPTION |
|---|---|
| 1 | Brake A |
| 2 | Brake B |
| 3 | Gear set 1 |
| 4 | Gear set 2 |
| 5 | Gear set 3 |
| 6 | Clutch E |
| 7 | Clutch C |
| 8 | Clutch D |
| 9 | Gear set 4 |
The shift elements, clutches and brakes are actuated hydraulically. Fluid pressure is applied to the required clutch and/or brake, pressing the plates together and allowing drive to be transmitted through the plates. The purpose of the shift elements is to perform power-on shifts with no interruption to traction and smooth transition between gear ratios.