2015 Buick LaCrosse Owner Manual - Page 215

9-30 Driving and Operating engine rpm is too high, nor to the next higher gear when the maximum engine rpm is reached. While in Manual Mode, the transmission will automatically downshift when the vehicle comes to a stop. This will allow for more power during take-off. When accelerating the vehicle from a stop in snowy and icy conditions, you may want to shift into 2 (Second) gear. A higher gear allows the vehicle to gain more traction on slippery surfaces. Drive Systems All-Wheel Drive Vehicles with this feature always send engine power to all four wheels. It is fully automatic, and adjusts itself as needed for road conditions. All-Wheel Drive (AWD) system performance will be automatically reduced when the compact spare tire is in use. To restore full AWD performance, and prevent excessive wear to the AWD system, replace the compact spare tire with a full-size tire as soon as possible. See Compact Spare Tire on page 10-77. Brakes Antilock Brake System (ABS) This vehicle has ABS, an advanced electronic braking system that helps prevent a braking skid. When the vehicle begins to drive away, ABS checks itself. A momentary motor or clicking noise might be heard while this test is going on, and it might even be noticed that the brake pedal moves a little. This is normal. If there is a problem with ABS, this warning light stays on. See Antilock Brake System (ABS) Warning Light on page 5-20.