2001 GMC Sonoma Owner's Manual - Page 101

Electronic Transfer Case The electronic transfer case switches are located to the right of the steering wheel. 4LO: This setting also engages your front axle to give you extra traction. You may never need 4LO. It sends the maximum power to all four wheels. You might choose 4LO if you were driving off-road in sand, mud or deep snow and climbing or descending steep hills. Indicator lights in the switches show you which setting you are in. The indicator lights will come on briefly when you turn on the ignition and one will stay on. If the lights do not come on, you should take your vehicle in for service. An indicator light will flash while shifting. It will remain illuminated when the shift is completed. Shifting from 2HI to 4HI Use these switches to shift into and out of four-wheel drive. You can choose among three driving settings: 2HI: This setting is for driving in most street and highway situations. Your front axle is not engaged in two-wheel drive. When this lamp is lit, it is about one-half as bright as the others. 4HI: This setting engages your front axle to help drive your vehicle. Use 4HI when you need extra traction, such as on snowy or icy roads, or in most off-road situations. Press and release the 4HI switch. This can be done at any speed, and the front axle will lock automatically. Shifting from 4HI to 2HI Press and release the 2HI switch. This can be done at any speed, and the front axle will unlock automatically. 2-30