1996 GMC Jimmy Owner's Manual - Page 204

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 sure to read and follow the instructions for the trailer brakes so you'll be able to install, adjust and maintain them properly. Your trailer's brake system can tap into the vehicle's hydraulic brake system only if: 0 Driving with a '7 ailer 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 your brakes. 0 If everything checks out this far, then make the brake fluid tap at the port on the master cylinder that sends fluid to the rear brakes. But don't usecopper 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 your vehicle, 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 a trailer: 0 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 your vehicle through a window in therear or another opening, drivewith your front, main heating or cooling system onand with the fan on any speed. Thiswill bring fresh, outside air into your vehicle. Do not use MAX A/C because it only recirculates the air inside yourvehicle. (See "Comfort Controls" in the Index.) i 4-51