2008 GMC ENVOY air suspension

Your Driving, the Road, and Your Vehicle..........4-2
Defensive Driving...........................................4-2
Drunk Driving.................................................4-2
Control of a Vehicle........................................4-3
Braking.........................................................4-3
Antilock Brake System (ABS)...........................4-4
Braking in Emergencies...................................4-5
Locking Rear Axle..........................................4-5
StabiliTrak
®System........................................4-6
Steering......................................................4-10
Off-Road Recovery.......................................4-12
Passing.......................................................4-12
Loss of Control.............................................4-12
Off-Road Driving...........................................4-13
Driving at Night............................................4-26
Driving in Rain and on Wet Roads..................4-27Before Leaving on a Long Trip.......................4-28
Highway Hypnosis........................................4-28
Hill and Mountain Roads................................4-29
Winter Driving..............................................4-30
If Your Vehicle is Stuck in Sand, Mud,
Ice, or Snow.............................................4-33
Rocking Your Vehicle to Get It Out.................4-34
Loading Your Vehicle....................................4-34
Adding a Snow Plow or Similar Equipment.......4-40
Towing..........................................................4-40
Towing Your Vehicle.....................................4-40
Recreational Vehicle Towing...........................4-40
Electronically Controlled
Air Suspension System..............................4-44
Towing a Trailer...........................................4-45
Section 4 Driving Your Vehicle
4-1

Your vehicle may have an electronically controlled
air suspension system that automatically keeps
your vehicle level as you load and unload
your vehicle. SeeElectronically Controlled Air
Suspension System on page 4-44for additional
information.
Certication/Tire Label
A vehicle specic Certication/Tire label is
found on the rear edge of the driver’s door.
The label shows the size of your vehicle’s original
tires and the ination pressures needed to
obtain the gross weight capacity of your vehicle.This is called Gross Vehicle Weight
Rating (GVWR). The GVWR includes the
weight of the vehicle, all occupants, fuel, cargo,
and trailer tongue weight, if pulling a trailer.
The Certication/Tire label also tells you the
maximum weights for the front and rear axles,
called Gross Axle Weight Rating (GAWR). To nd
out the actual loads on your front and rear axles,
you need to go to a weigh station and weigh your
vehicle. Your dealer can help you with this. Be sure
to spread out your load equally on both sides of the
centerline.
Never exceed the GVWR for your vehicle, or the
GAWR for either the front or rear axle.
And, if you do have a heavy load, you should
spread it out.
Similar appearing vehicles may have different
GVWRs and capacity weights. Please note your
vehicle’s Certication/Tire label or consult your
dealer for additional details.
4-38

{CAUTION:
Do not load your vehicle any heavier than
the Gross Vehicle Weight Rating (GVWR),
or either the maximum front or rear Gross
Axle Weight Rating (GAWR). If you do,
parts on your vehicle can break, and it
can change the way your vehicle handles.
These could cause you to lose control
and crash. Also, overloading can shorten
the life of your vehicle.
Using heavier suspension components to get
added durability might not change your vehicle’s
weight ratings. Ask your dealer to help you
load your vehicle the right way.
Notice:Overloading your vehicle may cause
damage. Repairs would not be covered by your
warranty. Do not overload your vehicle.
If you put things inside your vehicle — like
suitcases, tools, packages, or anything else — they
will go as fast as the vehicle goes. If you have to
stop or turn quickly, or if there is a crash, they will
keep going.
{CAUTION:
Things you put inside your vehicle can
strike and injure people in a sudden stop
or turn, or in a crash.
Put things in the cargo area of your
vehicle. Try to spread the weight
evenly.
Never stack heavier things, like
suitcases, inside the vehicle so that
some of them are above the tops of
the seats.
Do not leave an unsecured child
restraint in your vehicle.
When you carry something inside the
vehicle, secure it whenever you can.
Do not leave a seat folded down unless
you need to.
There is also important loading information for
off-road driving in this manual. See “Loading Your
Vehicle for Off-Road Driving” underOff-Road
Driving on page 4-13.
4-39

4. Follow the dolly manufacturer’s instructions to
attach and secure the vehicle being towed to
the dolly and then the loaded dolly to the tow
vehicle. Use an adequate clamping device to ensure
that the front wheels are locked into the straight
position.
5. Release the parking brake only after the vehicle
being towed is rmly attached to the towing
vehicle.
6. Turn the ignition to LOCK.
If the tow vehicle will not be started or driven for
six weeks or more, remove the battery cable
from the negative terminal (post) of the battery.
Electronically Controlled Air
Suspension System
Your vehicle may be equipped with an electronically
controlled air suspension system that automatically
keeps your vehicle level as you load and unload.
The system includes a compressor, two height
sensors and two air springs supporting the rear axle.The system also has an internal clock to prevent
overheating if the inator is used for prolonged periods.
If the system overheats, all leveling function stops
until the system cools down. During this time, the
indicator light on the air inator switch will be ashing.
The ignition has to be on for the system to inate,
in order to raise the vehicle to the standard ride height
after loading. The system can lower the vehicle to
the standard ride height after unloading with the ignition
on and also for up to 30 minutes after the ignition
has been turned off.
You may hear the compressor operating when you load
your vehicle, and periodically as the system adjusts
the vehicle to the standard ride height.
Load leveling will not function normally with the inator
hose attached to the inator outlet. Remove the inator
hose from the outlet during loading and unloading.
If the vehicle is parked for an extended period of time,
some bleed down of the suspension is normal. Upon
starting the vehicle, proper height will be achieved.
4-44

Overload Protection
The air suspension system is equipped with overload
protection. Overload protection is designed to protect
the air suspension system, and it is an indicator to
the driver that the vehicle is overloaded. When
the overload protection mode is on, it will not allow
damage to the air compressor. However, do not
overload the vehicle. SeeLoading Your Vehicle
on page 4-34.
If the suspension remains at a low height, the rear
axle load has exceeded GAWR (Gross Axle Weight
Rating). When the overload protection mode is activated,
the compressor operates for about 30 seconds to one
minute without raising the vehicle depending on the
amount of overload. This will continue each time
the ignition is turned on until the rear axle load is
reduced below GAWR.
Indicator Light
The indicator light on the inator switch in the rear
passenger compartment also serves as an indicator for
internal system error. If the indicator light is ashing
without the load leveling function or the inator being
active, turn off the ignition. The next day turn on the
ignition and check the indicator light. The vehicle can
be driven with the light ashing, but if it is you should
have the vehicle serviced as soon as possible.
Towing a Trailer
{CAUTION:
If you do not use the correct equipment and
drive properly, you can lose control when you
pull a trailer. For example, if the trailer is too
heavy, the brakes may not work well — or even
at all. You and your passengers could be
seriously injured. You may also damage your
vehicle; the resulting repairs would not be
covered by your warranty. Pull a trailer only if
you have followed all the steps in this section.
Ask your dealer/retailer for advice and
information about towing a trailer with
your vehicle.
Notice:Pulling a trailer improperly can damage
your vehicle and result in costly repairs that would
not be covered by your warranty. Always follow
the instructions in this section and check with your
dealer/retailer for more information about towing
a trailer with your vehicle.
To identify the trailering capacity of your vehicle, you
should read the information in “Weight of the Trailer” that
appears later in this section.
4-45

Tire Chains
{CAUTION:
Do not use tire chains. There is not enough
clearance. Tire chains used on a vehicle
without the proper amount of clearance can
cause damage to the brakes, suspension, or
other vehicle parts. The area damaged by the
tire chains could cause you to lose control of
your vehicle and you or others may be injured in
a crash. Use another type of traction device only
if its manufacturer recommends it for use on
your vehicle and tire size combination and road
conditions. Follow that manufacturer’s
instructions. To help avoid damage to your
vehicle, drive slowly, re-adjust or remove the
device if it is contacting your vehicle, and do
not spin your wheels. If you do nd traction
devices that will t, install them on the
rear tires.
Accessory Inator
Your vehicle may have an accessory inator system.
You can inate things like basketballs and bicycle tires.
You can also use it to bring your tire pressure up to
the proper pressure. It is not designed to inate large
objects which will require more than ve minutes to
inate, such as an air mattress.
The accessory inator is
located in the rear
compartment on the
driver’s side of the vehicle
behind an access cover,
near the liftgate opening.
To remove the cover, push in on the tab to access the
inator.
You may have an air inator kit that is located in the
glove compartment. It includes a 22 ft (6.7 m) hose with
three nozzle adapters.
5-80

To use the accessory inator:
1. Attach the appropriate nozzle adapter to the end of
the hose, if required.
{CAUTION:
Inating something too much can make it
explode, and you or others could be injured.
Be sure to read the inator instructions, and
inate any object only to its recommended
pressure.
2. Attach that end of the hose to the object you wish
to inate.
3. Attach the other end of the hose to the outlet.
4. Press and release the switch to turn the air inator
on. The indicator light will remain on when the
inator is running.
The system has an internal clock to prevent the
system from overheating. The system will allow
about ve minutes of running time, then the
compressor will stop. The indicator light will then
begin to ash. When the indicator is off, the inator
can be started again by pressing the switch. If the
compressor is still hot, it may only run for a short time
before shutting off again.
5. Press and release the switch to turn the inator off.Place the inator kit tools in the pouch and store it in
its proper location. Remove the inator hose from
the outlet during loading and unloading. Load leveling
will not function with the inator hose attached to
the inator outlet. SeeElectronically Controlled Air
Suspension System on page 4-44for more information.
To reinstall the cover, line up the tabs at the back of
the cover, put it in place and latch the tabs.
A continuous ashing indicator light may also indicate a
malfunction in the air suspension system. See
Electronically Controlled Air Suspension System on
page 4-44for more information.
If a Tire Goes Flat
It is unusual for a tire to blowout while you are driving,
especially if you maintain your vehicle’s tires properly.
If air goes out of a tire, it is much more likely to leak out
slowly. But if you should ever have a blowout, here
are a few tips about what to expect and what to do:
If a front tire fails, the at tire creates a drag that pulls
the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel rmly.
Steer to maintain lane position, and then gently brake
to a stop well out of the traffic lane.
5-81

Fuses Usage
1Electrically-Controlled Air
Suspension
2Passenger Side High-Beam
HeadlampFuses Usage
3Passenger Side Low-Beam
Headlamp
4 Back-Up Trailer Lamps L6 Engine
5-111