Buick 1998 Century Owner's Manual page 216

Hitches
Safety Chains
It's important to have the correct hitch equipment,
Crosswinds, large trucks going by and rough roads are a
few reasons why you'll need the right hitch. Here are
some rules to follow:
The rear bumper on your vehicle is not intended for
hitches. Do not attach rental hitches or other
bumper-type hitches to it. Use only a frame-mounted
hitch that does not attach to the bumper.
Will you have to make any holes in the body of your
vehicle when you install a trailer hitch? If you do,
then be sure to seal the holes later when you remove
the hitch. If you don't seal them, deadly carbon
monoxide (CO) from your exhaust can get into your
vehicle (see "Carbon Monoxide" in the Index). Dirt
and water can, too.
You should always attach chains between your vehicle
and your trailer. Cross the safety chains under the tongue
of the trailer so that the tongue will not drop to the road
if it becomes separated from the hitch. Instructions
about safety chains may be provided by the hitch
manufacturer or by the trailer manufacturer. Follow the
manufacturer's recommendation for attaching safety
chains and do not attach them to the bumper. Always
leave just enough slack so you can turn with your rig.
And, never allow safety chains to drag on the ground.
Trailer Brakes
Because you have anti-lock brakes, do not try to tap into
your vehicle's brake system. If you do, both brake
systems won't work well, or at all.
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