1999 GMC Suburban Owner's Manual - Page 225

yellowblue Four-Wheel Drive Vehicles Use the following procedure to correctly tow your vehicle on all four wheels: 1. Firmly set the parking brake. 2. Place the transmission in PARK (P). 3. Securely attach the vehicle being towed to the tow vehicle. 4. With the engine running, shift the transfer case to NEUTRAL (N). See "Four-Wheel Drive" in the Index for the proper procedure to select the neutral position for your vehicle. 5. Release the parking brake only after the vehicle being towed is firmly attached to the towing vehicle. 6. Turn the ignition to OFF. The OFF position unlocks the steering column and reduces battery drain. Unlocking the steering column will allow the proper movement of the front wheels and tires during towing. CAUTION: Shifting the transfer case into NEUTRAL (N) can cause your vehicle to roll even if the transmission is in PARK (P), for an automatic transmission. You or others could be injured. Make sure the parking brake is firmly set before you shift the transfer case into NEUTRAL (N). 4-43