tow MERCEDES-BENZ ML320 1997 Complete Owner's Manual

176 Driving instructions
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Caution!
When driving down long and steep grades, relieve the
load on the brakes by shifting into a lower gear to use
the engine’s braking power. This helps prevent
overheating of the brakes and reduces brake pad wear.
After hard braking, it is advisable to drive on for some
time, rather than immediately parking, so the air stream
will cool down the brakes faster.
Driving off
Apply the service brakes to test them briefly after
driving off. Perform this procedure only when the road
is clear of other traffic.
Warm up the engine smoothly. Do not place full load on
the engine until the operating temperature has been
reached.
When starting off on a slippery surface, do not allow one
drive wheel to spin for an extended period with the ESP
switched off. Doing so may cause serious damage to the
drive train which is not covered by the Mercedes-Benz
Limited Warranty.Parking
Important!
It is advisable to set the parking brake whenever
parking or leaving the vehicle. In addition, move
selector lever to position “P”.
When parking on hills, always set the parking brake.
Wa r n i n g !
To reduce the risk of personal injury as a result of
vehicle movement, before
turning off the engine
and leaving the vehicle, always:
1. Keep right foot on the service brake pedal.
2. Firmly depress parking brake pedal.
3. Move the selector lever to position “P”.
4. Slowly release the service brake pedal.
5. Turn front wheels towards the road curb.
6. Turn the key to steering lock position 0 and
remove.
7. Take the key and lock vehicle when leaving.

177 Driving instructions
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cluster displayPractical hints Car care Index Tires
Tread wear indicators (TWI) are required by law. These
indicators are located in six places on the tread
circumference and become visible at a tread depth of
approximately
1/16in (1.5 mm), at which point the tire is
considered worn and should be replaced.
The tread wear indicator appears as a solid band across
the tread.
Wa r n i n g !
If you feel a sudden significant vibration or ride
disturbance, or you suspect that possible damage to
your vehicle has occurred, you should turn on the
hazard warning f lashers, carefully slow down, and
drive with caution to an area which is a safe
distance from the roadway.Inspect the tires and under the vehicle for possible
damage. If the vehicle or tires appear unsafe, have
it towed to the nearest Mercedes-Benz Light Truck
Center or tire dealer for repairs.
Wa r n i n g !
Do not allow your tires to wear down too far. As
tread depth approaches
1/16in (1.5 mm), the
adhesion properties on a wet road are sharply
reduced.
Depending upon the weather and / or road surface
(conditions), the tire traction varies widely.

184 Driving instructions
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Checklist before off-road driving
•Tires: Check the tread depth and maintain specified
tire pressure (see tire pressure label inside the fuel
filler flap). Check tires for possible damage and
remove foreign objects. The valve caps must be
mounted.
•Rims: Dented or bent rims can cause tire pressure
loss and damage the tire beads. For this reason
change rims before driving off-road.
• Vehicle tool kit: Check if the vehicle jack is
functional. In all cases take the vehicle tool kit, a
strong tow rope, a shovel and a small plank (to put
under the vehicle jack on sandy soil) with you.Driving in steep terrain
Slope angle:
126° (ML 320 and ML 430)
23° (ML 55 AMG)
226° (ML 320 and ML 430)
21° (ML 55 AMG)
Switch to LOW RANGE mode before starting to drive up
or down steep inclines, see page 209.
Maximum vehicle climbing ability is a 60% grade.
1
2

189 Driving instructions
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Off-road driving increases strain on the vehicle.
We recommend that you inspect the vehicle for possible
damage after each off-road trip. Recognizing any
damage and a subsequent timely repair reduces the
chance of a possible breakdown or accident later on.
Proceed as follows:
•Switch off the LOW RANGE mode, see page 209.
•Remove excessive dirt from tires, wheels, wheel
housings, and underbody. For instance, after driving
in mud, clean the radiator, chassis, engine, brakes,
and wheels from extreme dirt, using a strong jet of
water.
•Inspect frame, oil pan, brake hoses, etc., as well as
vehicle underbody for possible damage.
•Check tires for possible damage, clean all exterior
lamps, and conduct a brake test.•Check for brush or branches caught in the
undercarriage. They could increase the possibility of
a fire, as well as cut fuel and / or brake lines,
puncture rubber bellows of the axles or drive shafts.
Wa r n i n g !
If you feel a sudden significant vibration or ride
disturbance, or you suspect that possible damage to
your vehicle has occurred, you should turn on the
hazard warning flashers, carefully slow down, and
drive with caution to an area which is a safe
distance from the roadway.Inspect the tires and under the vehicle for possible
damage. If the vehicle or tires appear unsafe, have
it towed to the nearest Mercedes-Benz Light Truck
Center or tire dealer for repairs.

190 Driving instructions
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Trailer towingTrailer Hitches
Only install a trailer hitch receiver approved for your
vehicle. For information on availability and installation,
please see your authorized Mercedes-Benz Light Truck
Center.
The bumpers on your vehicle are not designed for use
with clamp-type hitches. Do not attach rental hitches or
other bumper-type hitches to them.
To reduce the possibility of damage, remove the hitch
ball adaptor from the receiver when not in use.
Wa r n i n g !
Failure to use proper equipment and driving
technique can result in a loss of vehicle control
when towing a trailer.Improper towing or failure to follow the
instructions contained in this guide can result in
serious injury. Follow the guidelines below
carefully to assure safe trailer operation.Ask your authorized Mercedes-Benz Light Truck
Center should you require an explanation of
information contained in this guide.

191 Driving instructions
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The vehicle is prewired to accept the seven-wire harness
included in the Mercedes-Benz approved trailer hitch
receiver kit. An additional four-pole conversion plug is
included in the Mercedes-Benz supplied trailer hitch
receiver kit. For further information, please see your
authorized Mercedes-Benz Light Truck Center.
In order to prevent possible damage to the vehicle’s
electrical system by incorrectly installing the trailer
wiring plug, we recommend having the harness
connected at an authorized Mercedes-Benz Light Truck
Center.Vehicle and trailer weights and ratings
Gross Vehicle Weight Rating (GVWR) is the maximum
permissible vehicle weight: 6005 lbs. (2724 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 maximum
permissible trailer weight to be towed:
5000 lbs. (2260 kg)
Trailer Tongue Weight Rating (TWR) is the maximum
permissible weight of the trailer tongue:
[500 lbs. (225 kg) limit for MB approved hitch receiver] front
rear2755 lbs.
3527 lbs.(1250 kg)
(1600 kg)

192 Driving instructions
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Loading a trailer
When loading a trailer, you should observe 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
selected when determining how the vehicle and trailer
are loaded.
We recommend loading the trailer in such a manner
that it has a tongue weight (TW) between 10% and 15%
of the GTW.
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
To assure that the tow vehicle and trailer are in
compliance with the maximum permissible weight
limits, and to know the actual weights, have the loaded
rig (tow vehicle including driver, passengers and cargo,
trailer fully loaded) weighed on a commercial scale.
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 listed under
“Vehicle and trailer weight and ratings”.

193 Driving instructions
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cluster displayPractical hints Car care Index Attaching a trailer
Please observe maximum permitted trailer dimensions
(width and length).
Most states and all Canadian provinces require safety
chains between your tow vehicle and the trailer. The
chains should be crisscrossed under the trailer tongue.
They must be attached 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.
Most states and all Canadian provinces require a
separate brake system at various trailer weights.Caution!
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 function properly.
The provided vehicle electrical wiring harness for trailer
towing has a brake signal wire (color orange) for
hook-up to a brake controller.
Most states and all Canadian provinces require 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.
You should consider using a trailer sway control system.
For further information see your authorized
Mercedes-Benz Light Truck Center.

194 Driving instructions
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Tow in g a t r ai le r
There are many different laws, including speed limit
restrictions, having to do with trailer towing. Make sure
t ha t your rig will be lega l, not only for w here you reside,
but also for where you will be driving. A good source for
this information can be the police or local authorities.
Before you start driving with the trailer, check the
trailer hitch, break-away switch, safety chains, electrical
connections, lighting and tires. Also adjust the mirrors
to permit unobstructed view beyond rear of trailer.
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.
When towing a trailer, check occasionally to be sure that
the load is secure, and that lighting and trailer brakes
(if so equipped) are functioning properly.
Always secure items in the trailer to prevent load shifts
while driving.
Take into consideration that when towing a trailer, the
handling characteristics are different and less stable
from those when operating the vehicle without a trailer.
It is important to avoid sudden maneuvers.The vehicle and trailer combination is heavier, and
therefore is limited in acceleration and climbing ability,
and requires longer stopping distances. It is more prone
to reacting to side wind gusts, and requires more
sensitive steering input.
In order to gain skill and an understanding of the
vehicle’s behavior, you should practice turning,
stopping and backing up in an area which is free from
traffic.
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.
Caution!
If the trailer should begin to sway, reduce 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 trailer by
increasing the speed or oversteering and stepping on
the brakes.
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 reduces the
chance of engine overloading and / or overheating.

195 Driving instructions
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cluster displayPractical hints Car care Index At very steep inclines, not manageable with selector
lever in position “1”, switch transfer case to LOW
RANGE, see page 209 for instructions on how to engage
LOW RANGE.
When going down a long hill, shift into a lower gear and
use the engine’s braking effect. Avoid riding the brakes,
thus overheating the vehicle and trailer brakes.
If the engine coolant rises to an extremely high
temperature (coolant temperature needle approaching
the red zone) when the air conditioner is on, turn off the
air conditioner. 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.
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 return to your lane.Parking
Wa r n i n g !
To reduce the risk of personal injury, or damage to
the vehicle powertrain, as a result of vehicle/trailer
movement, always:1. Keep right foot on brake pedal.2. Shift gear selector lever to position “N”.3. Have a second person place wheel chocks on
downhill side of left and right trailer wheels.4. Slowly release brake pedal and let vehicle and
trailer roll into chocks until stopped.5. Firmly depress parking brake pedal.6. Move gear selector lever to position “P”.7. On inclines turn front wheels towards the road
curb.