On Vehicle

GENERAL DESCRIPTION





This section provides information relating to the Powertrain 4L80-E transmissions fitted to the 4.0 liter supercharged engine (4.OL SC) and to the 6.0 liter engine (6.OL).

The Powertrain 4L80-E is a four-speed, high torque capacity, electronically controlled automatic transmission, which comprises a torque converter with lock-up direct drive clutch and three planetary gear sets. Five multiple disk clutches, one intermediate sprag clutch assembly, two roller clutch assemblies and two band assemblies provide the drive elements necessary for correct sequential gear engagement and operation.

The torque converter containing a pump, a turbine (rotor), a stator assembly, and a clutch pressure disk splined to the turbine, acts as a fluid coupling for smooth torque transmission from the engine. The converter also supplies additional torque multiplication when necessary, and the torque converter clutch (TCC) pressure disk provides a mechanical direct drive or 'lock-up' above a certain speed in top gear for greater fuel economy.

Gearshift operations are controlled from the Transmission Control Module (TCM), which governs the electronically controlled valve body situated within the transmission.

Three planetary gear sets provide reverse and the four forward ratios, the changing of which is fully automatic in relation to load, vehicle speed and throttle opening. The Transmission Control Module receives and integrates various vehicle sensor input signals, and transmits operating signals to the solenoids located in the control valve assembly. These solenoids govern the transmission operating pressures, up-shift and downshift gear selection patterns and also the torque converter clutch operation by pulse width modulated control.


Gear Ranges

Selectable gear positions are: P - Park, R - Reverse, N - Neutral, D - Drive, 3, 2.

P - Park position of the shift lever provides a mechanical locking of the output shaft of the transmission, and as such, must only be engaged when the the vehicle is stationary. In addition, and for extra safety, the handbrake should also be applied. It is necessary to have the ignition ON and the footbrake applied to move the shift lever from the Park position. For ignition key removal the shift lever must be in the Park position. The engine can be started in the Park position.

R - Reverse enables the vehicle to be operated in a rearwards direction. The engine cannot be started in the Reverse position.

N - Neutral position enables the engine to be started and operated without driving the vehicle. It also allows the vehicle to be moved manually for access, ie for removal of the propeller shaft.

D - Drive position allows the automatic selection of all four forward gear ratios during normal driving conditions for maximum efficiency and fuel economy. On acceleration, down-shifts are obtained by depressing the accelerator pedal or by manual selection. The engine cannot be started in this position.

3 - Manual third position allows automatic operation of the three lower gear ratios but inhibits selection of the fourth ratio. This position is used for towing a trailer or negotiating hilly terrain when greater engine braking control is required. The engine cannot be started in this position.

2 - Manual second position allows automatic operation of the two lower gear ratios but inhibits selection of the third and fourth ratios. This position is used for heavy traffic congestion or negotiating hilly terrain when even greater engine braking control is required than is provided by manual third. This ratio may be selected at any vehicle speed - even if the transmission is in third or fourth ratio, the transmission will immediately downshift to second gear provided the vehicle speed is below 137 km/h (85 mile/h). The engine cannot be started in this position.


Note: With the Performance Mode switch in the NORMAL position, the vehicle will pull away in second gear. However, if more than 75 percent of throttle is applied when the vehicle speed is between zero and 13 km/h (8 mile/h), then first gear will be selected. From 13 to 61 km/h (8 to 38 mile/h) first gear is obtainable by 'kick-down'. In 'sport' mode the vehicle pulls away in first gear and the transmission operates fully in all four forward gears.






Shift Speed Chart, 4.0 Supercharged





Shift Speed Chart, 6.0 V-12