1998 GMC Suburban Owner's Manual - Page 244

Trailer Brakes If your trailer weighs more than 1,000 lbs. (450 kg) loaded, then it needs its own brakes -- and they must be adequate. Be s ~ r to read and follow the instructions for e the trailer brakes so you'll be able to install, adjust and maintain them properly. Driving with a Trailer Your trailer brake system can tap into the vehicle's hydraulic brake system only if: The trailer parts can withstand 3,000 psi (20 650 kPa) of pressure. The trailer's brake system will use less than 0.02 cubic inch (0.3 cc) of fluid from your vehicle's master cylinder. Otherwise, both braking systems won't work well. You could even lose YOLK brakes. If everything checks out this far, make the brake tap at the port on the master cylinder that sends the fluid to the rear brakes. But don't use copper tubing for this. If you do, it will bend and finally break off. Use steel brake tubing. If you have a rear-most window open and you pull a trailer with yourvehicle, carbon monoxide (CO) could come into your vehicle. You can't see or smell CO. It can cause unconsciousness or death. (See "Engine Exhaust" in the Index.) To maximize your safety when towing trailer: a Have your exhaust system inspected for leaks, and make necessary repairs before starting on your trip. 0 Keep the rear-most windows closed. 0 If exhaust does come into yourvehicle through a window in the rear or another opening, drive with your front, main heating or cooling system on and with the fan on any speed. This bring fresh, will outside air into your vehicle. Do not use the recirculation button o r MAX because it only recirculates the air inside your vehicle. (See "Comfort Controls" in the Index.) 4-52