Chevrolet 2003 Astro Owner's Manual page 211

Hitches
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:
If you'll be pulling a trailer that, when loaded, will
weigh more than 2,000 Ibs. (900 kg.), be sure to
use a properly mounted, weight-distributing
hitch and sway control of the proper size. This
equipment is very important for proper vehicle
loading and good handling when you're driving.
Will you have to make any holes in the body of
your vehicle when you install a trailer hitch?
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. Never allow safety chains to drag on the ground.
Trailer Brakes
If your trailer weighs more than 1,000 Ibs (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 brake system can tap into your vehicle's
hydraulic brake system, except:
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. Dirt and water can, too.
Safety Chains
You should always attach chains between your vehicle
and your trailer. Cross the safety chains under the tongue
of the trailer to help prevent the tongue from contacting
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.
Don't tap into your vehicle's brake system if the
trailer's brake system will use more than 0.02 cubic
inch (0.3 cc) of fluid from your vehicle's master
cylinder. If it does, both braking systems won't work
well. You could even lose your brakes.
Will the trailer parts take 3,000 psi (20 650 kPa) of
pressure? If not, the trailer brake system must not
be used with your vehicle.
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.
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