1998 GMC Safari Owner's Manual - Page 217

Your trailer brake system can into your vehicle's tap hydraulic brake system, except: 0 Driving with a Trailer 0 0 If you havea rear-most window openand you pull a trailer with your vehicle, carbon monoxide (CO) could comeinto your vehicle. You can't see Will the trailer parts take 3,000 psi (20 650 kPa) of pressure? If not, the trailer brake system must not be or smell CO. It can cause unconsciousnessor used with your vehicle. death. (See "Engine Exhaust" in Index.) To the maximize your safety when towing a trailer: If everything checksout this far, then make the brake fluid tap at the port on the master cylinder that sends 0 Have your exhaust system inspected for fluid to the rear brakes. But don't use copper tubing leaks, and make necessaryrepairs before for this. If you do, it will bend and finally break off. starting on your trip. Use steel brake tubing.. 0 Keep the rear-most windows closed. 0 If exhaust does come into your vehicle through a window in the rear or another opening, drive with your front, main heating or cooling system on with the and will fan on any speed. This bring fresh, outside air into your vehicle. Do not use MAX A/C because it only recirculates the air inside your vehicle. (See "Comfort Controls" inthe Index.) Don't tap into your vehicle's brake system the if trailer's brake system will use more than cubic 0.02 inch (6.3 cc) of fluid from your vehicle's master cylinder. If it does, both braking systems won't work well. You could evenlose your brakes. 4-33