Transmission General Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: 4T40E & 4T45E Fully Automatic Front Wheel Drive Electronically Controlled Transaxle

Courtesy of GENERAL MOTORS CORP.

NOTE: Saturn automatic transaxle fluid (ATF), P/N 21005966 and P/N 21019223, is not compatible with this transaxle. If Saturn ATF is used, transaxle damage will result.

The 4T40E and 4T45E are fully automatic front wheel drive electronically controlled transaxles. The 4T40/45E provide four forward ranges including overdrive and one reverse gear range. The PCM/TCM controls shift points by means of two shift solenoids. A vane type pump supplies oil pressure. The PCM/TCM regulates oil pressure by means of pressure control solenoid (PCS).

The transaxle can be operated in any one of the following seven modes:

R - Reverse allows vehicle to be operated in a rearward direction.
P - Park position prevents vehicle from rolling either forward or backward. For safety reasons, use parking brake in addition to Park position.
N - Neutral allows engine to be started and operated while driving vehicle. If necessary, this position may be selected in order to restart engine with vehicle moving.
D - Overdrive is used for all normal driving conditions. Overdrive provides four gear ratios plus a converter clutch operation. Depress accelerator in order to downshift for safe passing.
3 - Drive position is used for city traffic, hilly terrain, and trailer towing. Drive provides three gear ranges and prevents transaxle from operating in fourth gear. Depress accelerator in order to downshift.
2 - Manual Second provides two gear ratios under most operating conditions. Manual Second provides acceleration and engine braking. This gear range may be selected at any vehicle speed, but transaxle will not downshift into Second gear until vehicle speed drops below approximately 100 km/h (62 mph).
1 - Manual Low provides maximum engine braking. This gear range may be selected at any vehicle speed, but transaxle will not downshift into First gear until vehicle speed drops below approximately 60 km/h (37 mph).