GMC 1999 Sierra 1500 Pickup Owner's Manual page 237

Driving with a Trailer
Towing a trailer requires a certain amount of experience. Before setting out
for the open road, you'll want to get to know your rig. Acquaint yourself with
the feel of handling and braking with the added weight of the trailer. And
always keep in mind that the vehicle you are driving is now a good deal
longer and not nearly so responsive as your vehicle is by itself.
Before you start, check the trailer hitch and platform, safety chains, electrical
connector, lights, tires and mirror adjustment. If the trailer has electric brakes,
start your vehicle and trailer moving and then apply the trailer brake controller
by hand to be sure the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to be sure that the load is secure, and
that the lights and any trailer brakes are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as you would when
driving your vehicle without a trailer. This can help you avoid situations that
require heavy braking and sudden turns.
Passing
You'll need more passing distance up ahead when you're towing a trailer.
And, because you're a good deal longer, you'll need to go much farther
beyond the passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand. Then, to move the
trailer left, just move your hand to the left. To move the trailer to the right,
move your hand to the right. Always back up slowly and, if possible, have
someone guide you.
Making Turns
When you're turning with a trailer, make wider turns than normal. Do this so
your trailer wheels won't strike soft shoulders, curbs, road signs, trees, or
other objects. Avoid jerky or sudden maneuvers. Signal well in advance.
Turn Signals When Towing a Trailer
When you tow a trailer, your vehicle has to have a different turn signal
flasher and extra wiring. The green arrows on your instrument panel will flash
whenever you signal a turn or lane change. Properly hooked up, the trailer
lights will also flash, telling other drivers you're about to turn, change lanes,
or stop.
When towing a trailer, the green arrows on your instrument panel will flash for
turns even if the bulbs on the trailer are burned out. Thus, you may think
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