1999 Chevrolet Blazer Owner's Manual - Page 247

yellowblue Your trailer's brake system can tap into the vehicle's hydraulic brake system only if: Driving with a Trailer D The trailer parts can withstand 3,000 psi (20 650 kPa) of pressure. CAUTION: 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: D Have your exhaust system inspected for leaks, and make necessary repairs before starting on your trip. D Keep the rear-most windows closed. D 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 and with the fan on any speed. This will bring fresh, outside air into your vehicle. Do not use MAX A/C or RECIRCULATION because it only recirculates the air inside your vehicle. (See "Comfort Controls" in the Index.) D 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. 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 use copper tubing for this. If you do, it will bend and finally break off. Use steel brake tubing. 4-51