Transmission General Description

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The 4T65-E is a fully automatic front wheel drive electronically controlled transmission. The 4T65-E provides 4 forward ranges, including overdrive. The powertrain control module/transmission control module (PCM/TCM) controls shift points by means of 2 shift solenoids. A vane-type oil pump supplies the oil pressure. The PCM/TCM regulates oil pressure by means of a pressure control solenoid valve.

All vehicles equipped with a 4T65-E transmission have an electronically controlled capacity clutch (ECCC) system. In the ECCC system, the pressure plate does not fully lock to the torque converter cover. It is instead, precisely controlled to maintain a small amount of slippage between the engine and the turbine, reducing driveline torsional disturbances.

You can operate the transmission in any 1 of the following 7 modes:

P - PARK position prevents the vehicle from rolling forward or backward. For safety reasons, use the parking brake in addition to the PARK position.
R - REVERSE allows the vehicle to be operated in a rearward direction.
N - NEUTRAL allows the engine to be started and operated while driving the vehicle. If necessary, you may select this position in order to start the engine with the vehicle moving.
D - OVERDRIVE is used for all normal driving conditions. OVERDRIVE provides 4 gear ratios plus a converter clutch operation. Depress the accelerator in order to downshift for safe passing.
3 - DRIVE position is used for city traffic and hilly terrain. DRIVE provides 3 gear ranges and DRIVE range prevents the transmission from operating in fourth gear. Depress the accelerator in order to downshift.
2 - Manual Second provides 2 gear ratios under most operating conditions. Manual Second provides acceleration and engine braking. You may select this range at any vehicle speed. The transmission does not downshift into Second gear until the vehicle speed drops below approximately 100 km/h (62 mph).
1 - Manual Lo provides maximum engine braking. You may select this range at any vehicle speed. The transmission does not downshift into First gear until the vehicle speed drops below approximately 60 km/h (37 mph).