Mercedes-Benz ML320. Manual — part 95

207

Operation

Driving instructions

Trailer hitches

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Only install a trailer hitch receiver ap-
proved for your vehicle.

For information on availability and in-
stallation, see your authorized
Mercedes-Benz Light Truck Center.

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The bumpers on your vehicle are not
designed for use with clamp-type hitch-
es.

Do not attach rental hitches or other
bumper-type hitches to them.

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To reduce the possibility of damage, re-
move the hitch ball adaptor from the
receiver when not in use.

Electrical connections

The vehicle is prewired to accept the sev-
en-wire harness included in the
Mercedes-Benz approved trailer hitch re-
ceiver kit.

An additional four-pole conversion plug is
included in the Mercedes-Benz supplied
trailer hitch receiver kit.

For further information, see your autho-
rized Mercedes-Benz Light Truck Center.

Vehicle and trailer weights and ratings

Gross Vehicle Weight Rating (GVWR) is the
maximum permissible vehicle weight:
6614 lbs (3000 kg).

Gross Vehicle Weight (GVW):
Comprises weight of vehicle including fuel,
tools, spare wheel, installed accessories,
passengers, cargo and trailer tongue. It
must never exceed the GVWR.

Gross Axle Weight Rating (GAWR) is the
maximum permissible axle weight:

Gross Trailer Weight (GTW) is the maxi-
mum permissible trailer weight to be
towed:
5000 lbs (2260 kg).

Trailer Tongue Weight Rating (TWR) is the
maximum permissible weight on the trailer
tongue:
500 lbs (225 kg) limit for Mercedes-Benz
approved hitch receiver.

front
rear

2976 lbs
3858 lbs

(1350 kg)
(1750 kg)

208

Operation

Driving instructions

Loading a trailer

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When loading a trailer, you should ob-
serve that neither the permissible GTW,
nor the GVWR are exceeded.

Maximum permissible values are listed
on the safety compliance certification
labels for the vehicle and for the trailer
to be towed.
The lowest value listed must be select-
ed when determining how the vehicle
and trailer are loaded.

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The tongue weight at the hitch ball
must be added to the GVW to prevent
exceeding your Mercedes-Benz tow
vehicle’s rear GAWR.

Checking weights of vehicle and trailer

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To assure that the tow vehicle and trail-
er are in compliance with the maximum
permissible weight limits have the load-
ed rig (tow vehicle including driver, pas-
sengers and cargo, trailer fully loaded)
weighed on a commercial scale.

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Check the vehicle’s front and rear
Gross Axle Weight (GAW), the GTW and
TW.

The values as measured must not be
exceeded, according to the weight list-
ed under “Vehicle and trailer weight
and ratings”.

Attaching a trailer

Observe maximum permitted trailer
dimensions (width and length).

Most states and all Canadian provinces
require

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safety chains between your tow vehicle
and the trailer.

The chains should be crisscrossed un-
der the trailer tongue. They must be at-
tached to the hitch receiver, and not to
the vehicle’s bumper or axle.

Be sure to leave enough slack in the
chains to permit turning corners.

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a separate brake system at various
trailer weights.

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a break-away switch on trailers with a
separate brake system.

The switch activates the trailer brakes
in the possible event that the trailer
might separate from the tow vehicle.

i

We recommend loading the trailer in
such a manner that it has a tongue
weight (TW) between 10% and 15% of
the GTW.

209

Operation

Driving instructions

Towing a trailer

There are many different laws, including
speed limit restrictions, having to do with
trailer towing. Make sure your rig will be le-
gal, not only for where you reside, but also
for where you will be driving. A good
source for this information can be the po-
lice or local authorities.

Note the following points, when driving
with the trailer:

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In order to gain skill and an under-
standing of the vehicle’s behavior, you
should practice turning, stopping and
backing up in an area which is free from
traffic.

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Before you start driving check the

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trailer hitch

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break-away switch

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safety chains

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electrical connections

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lighting and tires

Adjust the mirrors to permit unobstructed
view beyond rear of trailer.

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If the trailer has electric brakes, start
your vehicle and trailer moving slowly,
and then apply only the trailer brake
controller by hand to be sure the
brakes are working properly.

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Always secure items in the trailer to
prevent load shifts while driving.

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When towing a trailer, check occasion-
ally to be sure that the load is secure,
and that lighting and trailer brakes (if
so equipped) are functioning properly.

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Take into consideration that when tow-
ing a trailer, the handling characteris-
tics are different and less stable from
those when operating the vehicle with-
out a trailer.

It is important to avoid sudden maneu-
vers.

!

Do not connect a trailer brake system
(if trailer is so equipped) directly to the
vehicle’s hydraulic brake system, as
your vehicle is equipped with antilock
brakes. If you do, neither the vehicle’s
brakes nor the trailer’s brakes will func-
tion properly.

i

The provided vehicle electrical wiring
harness for trailer towing has a brake
signal wire (color orange) for hook-up
to a brake controller.

You should consider using a trailer
sway control system. For further infor-
mation see your authorized
Mercedes-Benz Light Truck Center.

210

Operation

Driving instructions

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The vehicle and trailer combination is
heavier, and therefore is limited in ac-
celeration and climbing ability, and re-
quires longer stopping distances.

It is more prone to reacting to side wind
gusts, and requires more sensitive
steering input.

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If possible, do not brake abruptly, but
rather engage the brake slightly at first
to permit the trailer to activate its
brake. Then increase the braking force.

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If the transmission hunts between
gears on inclines, manually shift to a
lower gear (select 4, 3, 2 or 1).

A lower gear and reduction of speed re-
duces the chance of engine overload-
ing and/or overheating.

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On very steep inclines, not manageable
with gear selector lever in position 1,
switch transfer case to LOW RANGE
mode (

컄

page 125).

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When going down a long hill, shift into
a lower gear and use the engine’s brak-
ing effect.

Avoid riding the brakes, thus overheat-
ing the vehicle and trailer brakes.

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If the engine coolant rises to an ex-
tremely high temperature (coolant tem-
perature needle approaching the red
zone) when the air conditioning is on,
turn off the air conditioning system.

Engine coolant heat can be additionally
vented by opening the windows,
switching the climate control fan speed
to high and setting the temperature
control to the maximum hot position.

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Extreme care must be exercised since
your vehicle with a trailer will require
additional passing distance ahead than
when driving without a trailer.

Because your vehicle and trailer is
longer than your vehicle alone, you will
also need to go much farther ahead of
the passed vehicle before you can re-
turn to your lane.

!

If the trailer should begin to sway, re-
duce the vehicle’s speed and use the
brake controller by hand to straighten
out the vehicle and trailer.

In no case should you attempt to
straighten out the tow vehicle and trail-
er by increasing the speed or overstee-
ring and stepping on the brakes.