GM Service Manual Online
For 1990-2009 cars only

The 4T40-E is a fully automatic front wheel drive electronically controlled transmission. The 4T40-E provides four forward ranges including overdrive and one reverse gear range. The PCM controls shift points by means of two shift solenoids. A vane type pump supplies the oil pressure. The PCM regulates oil pressure by means of the Pressure Control Solenoid (PCS).

You can operate the transmission in any one of the following seven 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 for normal driving with the automatic transaxle. It provides the best fuel economy for your vehicle.
    • I -- Intermediate position is also used for normal driving. However, it reduces vehicle speed without using your brakes for slight downgrades where the vehicle would otherwise accelerate due to steepness of grade. If constant upshifting or downshifting occurs while driving up steep hills, this position can be used to prevent repetitive types of shifts. You might choose Intermediate (I) instead of Drive (D) when driving on hilly, winding roads and when towing a trailer, so that there is less shifting between gears.
    • L -- Low position reduces vehicle speed more than Intermediate (I) without actually using your brakes. You can use it on very steep hills, or in deep snow or mud. If the shift lever is put in Low (L), the transaxle will not shift into Low (L) until the vehicle is going slowly enough.