GM Service Manual Online
For 1990-2009 cars only

The Hydra-Matic 3T40 transmission is a fully automatic unit for front wheel drive vehicles. The 3T40 provides three forward gear ranges and a reverse. Throttle opening controls the oil pressure and shift points.

You can operate the transmission in any one of the following six modes:

    • P -- Park position prevents the vehicle from rolling either 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 restart the engine with the vehicle moving.
    • D -- Drive position is used for normal driving conditions. Drive position provides three gear ratios plus a converter clutch operation. Downshifts are available for safe passing by depressing the accelerator.
    • 2 -- Manual second provides acceleration and engine braking. You may select this range at any vehicle speed.
    • 1 -- Manual Low provides maximum engine braking. You may select this range at any vehicle speed.