GM Service Manual Online
For 1990-2009 cars only

The 4T45-E is a fully automatic front wheel drive electronically controlled transmission. The 4T45-E provides four forward ranges including overdrive and one reverse gear range. The powertrain control module (PCM)/transmission control module (TCM) controls shift points by means of 2 shift solenoids. A vane type pump supplies the oil pressure. The PCM/TCM regulates oil pressure by means of the pressure control (PC) solenoid.

You can operate the transmission in any one of the following 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 -- Overdrive is used for all normal driving conditions. Overdrive provides four gear ratios plus a converter clutch operation. Depress the accelerator in order to downshift for safe passing.
    • M -- Placing the vehicle in this drive position places the vehicle in 3rd gear. This drive position also activates the Driver Shift Control System. The Driver Shift Control System is also referred to as TAP Shift. Refer to TAP Shift Operation .