WARREN, Mich. -- General Motors announced it will begin installing vehicle stability enhancement systems in GMC Savana and Chevrolet Express 15-passenger vans during the 2004 model-year production cycle.

"By adding this system, we will take what we believe is already a very safe vehicle and make it even better," said Ray Chess, GM vehicle line executive for commercial trucks and vans.

The system will be standard on all 15-passenger vans. It will be incorporated as an interim change during the 2004 production year, which begins later this summer.

Vehicle stability enhancement systems (VSES) help drivers maintain control of vehicles during certain difficult driving conditions such as ice, snow, gravel, wet pavement and uneven road surfaces -- as well as in emergency lane changes or sharp turns to avoid a collision.

GM offers the system across its many models with the names StabiliTrak, Precision Control and Active Traction. The 15-passenger vans will be badged StabiliTrak.

VSES works by recognizing wheel skid. Sensors detect the difference between the steering wheel angle and the direction the driver is actually turning by "reading" the steering wheel position, the amount of sideways force in play, vehicle speed and the vehicle's response to steering wheel input.

The system then uses the brakes to enhance control of the vehicle's direction and to help keep it on course. It automatically reduces the engine torque and applies precise amounts of pressure to front right or left brakes to help keep the vehicle on track. These brake and engine interventions help realign the vehicle's actual path with that being steered by the driver.

GM began installing VSES in passenger cars in 1997, and now has more than 2 million equipped vehicles on the road.

"While vehicle stability enhancement systems do not directly prevent rollover crashes, they may help drivers avoid the conditions that cause them," said Robert C. Lange, GM executive director for structure and safety integration. "However, it is important to understand that no system is foolproof. That is why we will continue to educate our customers on the unique operating characteristics of full-size, extended passenger vans and that they should be operated only by experienced drivers."