1999 GMC Sonoma Owner's Manual - Page 84

yellowblue On automatic transmission equipped vehicles, if your transfer case does not shift into 4HI, your transmission indicator switch may require adjustment. With your transmission in NEUTRAL (N), press and release the 4HI switch. While the 4HI indicator light is flashing, shift your transmission into PARK (P). Wait until the 4HI indicator light remains illuminated before shifting your transmission into gear. This will get you into 4HI, but you should take your vehicle in for service to restore normal operation. Parking Brake To set the parking brake, hold the regular brake pedal down with your right foot. Push down the parking brake pedal with your left foot. If the ignition is on, the brake system warning light will come on. To release the parking brake hold the regular brake pedal down. Pull the BRAKE RELEASE lever fully. It is located on the bottom of the driver's side of the instrument panel. NOTICE: Driving with the parking brake on can cause your rear brakes to overheat. You may have to replace them, and you could also damage other parts of your vehicle. If you are towing a trailer and you must park on a hill, see "Towing a Trailer" in the Index. That section shows what to do first to keep the trailer from moving. 2-26