2008 GMC ENVOY trans release

Driving Downhill
When off-roading takes you downhill, you will want to
consider a number of things:
How steep is the downhill? Will I be able to maintain
vehicle control?
What is the surface like? Smooth? Rough?
Slippery? Hard-packed dirt? Gravel?
Are there hidden surface obstacles? Ruts? Logs?
Boulders?
What is at the bottom of the hill? Is there a hidden
creek bank or even a river bottom with large rocks?
If you decide you can go down a hill safely, then try
to keep your vehicle headed straight down, and use a
low gear. This way, engine drag can help the brakes and
they will not have to do all the work. Descend slowly,
keeping your vehicle under control at all times.
{CAUTION:
Heavy braking when going down a hill can
cause your brakes to overheat and fade.
This could cause loss of control and a serious
accident. Apply the brakes lightly when
descending a hill and use a low gear to
keep vehicle speed under control.There some things not to do when driving down a hill.
These are important because, if you ignore them,
you could lose control and have a serious accident:
When driving downhill, avoid turns that take you
across the incline of the hill. A hill that is not too steep
to drive down may be too steep to drive across. You
could roll over if you do not drive straight down.
Never go downhill with the transmission in
NEUTRAL (N). This is called “free-wheeling.”
The brakes will have to do all the work and could
overheat and fade.
Your vehicle is much more likely to stall when going
uphill. But if it happens when going downhill:
1. Stop your vehicle by applying the regular brakes.
Apply the parking brake.
2. Shift to PARK (P) and, while still braking, restart the
engine.
3. Shift back to a low gear, release the parking brake,
and drive straight down.
4. If the engine will not start, get out and get help.
4-21

Rocking Your Vehicle to Get It Out
First, turn the steering wheel left and right to clear the
area around the front wheels. For four-wheel-drive
vehicles, shift into Four-Wheel High. Turn off any traction
or stability system. SeeStabiliTrak
®System on page 4-6.
Then shift back and forth between REVERSE (R) and a
forward gear, spinning the wheels as little as possible.
To prevent transmission wear, wait until the wheels stop
spinning before shifting gears. Release the accelerator
pedal while you shift, and press lightly on the accelerator
pedal when the transmission is in gear. By slowly
spinning the wheels in the forward and reverse directions,
you will cause a rocking motion that could free your
vehicle. If that does not get your vehicle out after a few
tries, it might need to be towed out. If your vehicle does
need to be towed out, seeTowing Your Vehicle on
page 4-40.
Loading Your Vehicle
It is very important to know how much weight your
vehicle can carry. This weight is called the vehicle
capacity weight and includes the weight of all
occupants, cargo, and all nonfactory-installed
options. Two labels on your vehicle show how
much weight it was designed to carry, the Tire
and Loading Information label and the Certication/
Tire label.
{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.
4-34

4. Securely attach the vehicle being towed to the tow
vehicle.
{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer
case into NEUTRAL can cause your vehicle to
roll even if the transmission is in PARK (P).
You or others could be injured. Make sure the
parking brake is rmly set before you shift the
transfer case to NEUTRAL.
5. Shift the transfer case to NEUTRAL (N). See
Four-Wheel Drive on page 2-29for the proper
procedure to select the NEUTRAL (N) position
for your vehicle.
6. Release the parking brake only after the vehicle
being towed is rmly attached to the towing
vehicle.
7. Turn the ignition off.
After towing, see “Shifting Out of Neutral” under
Four-Wheel Drive on page 2-29.
Dolly Towing
Front Towing (Front Wheels Off
the Ground)
Two-Wheel-Drive Vehicles
Notice:If you tow a two-wheel-drive vehicle with
the rear wheels on the ground, the transmission
could be damaged. The repairs would not be
covered by your warranty. Never tow your vehicle
with the rear wheels on the ground.
Four-Wheel-Drive Vehicles
Four-wheel-drive vehicles can be dolly towed with the
rear wheels on the ground.
Use the following procedure to tow your vehicle:
1. Drive the vehicle onto the tow dolly.
2. Shift the automatic transmission to PARK (P).
3. Turn the engine off, but leave the ignition on.
4. Firmly set the parking brake.
5. Securely attach the vehicle being towed to
the dolly.
4-42

{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer
case into NEUTRAL can cause your vehicle to
roll even if the transmission is in PARK (P).
You or others could be injured. Make sure the
parking brake is rmly set before you shift the
transfer case to NEUTRAL.
6. Shift the transfer case to NEUTRAL (N). See
Four-Wheel Drive on page 2-29for the proper
procedure to select the NEUTRAL (N) position for
your vehicle.
7. Release the parking brake only after the vehicle
being towed is rmly attached to the towing
vehicle.
8. Turn the ignition off.
After towing, see “Shifting Out of Neutral” under
Four-Wheel Drive on page 2-29.
Rear Towing (Rear Wheels Off
the Ground)
(Two-Wheel or Four-Wheel-Drive Vehicles)
Use the following procedure to tow your vehicle from
the rear:
1. Drive the vehicle onto the dolly.
2. Firmly set the parking brake. SeeParking Brake on
page 2-33for more information.
3. Shift the transmission in PARK (P).
4-43

Parking on Hills
{CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.
But if you ever have to park your rig on a hill, here’s
how to do it:
1. Apply your regular brakes, but don’t shift into
PARK (P) yet. When parking uphill, turn your wheels
away from the curb. When parking downhill, turn
your wheels into the curb.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake, and then shift into PARK (P).
5. Release the regular brakes.
{CAUTION:
It can be dangerous to get out of your vehicle if
the shift lever is not fully in PARK (P) with the
parking brake rmly set. Your vehicle can roll.
If you have left the engine running, the vehicle
can move suddenly. You or others could be
injured. To be sure your vehicle will not move,
even when you are on fairly level ground, use
the steps that follow.
Always put the shift lever fully in PARK (P) with
the parking brake rmly set.
If the transfer case on four-wheel drive vehicles
is in NEUTRAL, your vehicle will be free to roll,
even if your shift lever is in PARK (P). So, be
sure the transfer case is in a drive gear — not
in NEUTRAL.
SeeFour-Wheel Drive on page 2-29.
4-54

When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
start your engine,
shift into a gear, and
release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission uid (don’t overll),
engine oil, axle lubricant, belt(s), cooling system and
brake system. Each of these is covered in this manual,
and the Index will help you nd them quickly. If you’re
trailering, it’s a good idea to review these sections before
you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
4-55

Service............................................................5-3
Accessories and Modications..........................5-3
California Proposition 65 Warning.....................5-4
California Perchlorate Materials Requirements.....5-4
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside of
Your Vehicle..............................................5-5
Fuel................................................................5-5
Gasoline Octane............................................5-6
Gasoline Specications....................................5-6
California Fuel...............................................5-6
Additives.......................................................5-7
Fuels in Foreign Countries...............................5-7
Filling the Tank..............................................5-8
Filling a Portable Fuel Container.....................5-10
Checking Things Under the Hood....................5-10
Hood Release..............................................5-11
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-16
Engine Oil Life System..................................5-19
Engine Air Cleaner/Filter................................5-21
Automatic Transmission Fluid.........................5-23
Engine Coolant.............................................5-26
Radiator Pressure Cap..................................5-28
Engine Overheating.......................................5-28
Cooling System............................................5-30Engine Fan Noise.........................................5-35
Power Steering Fluid.....................................5-36
Windshield Washer Fluid................................5-37
Brakes........................................................5-38
Battery........................................................5-41
Jump Starting...............................................5-42
Rear Axle.......................................................5-46
Four-Wheel Drive............................................5-47
Front Axle......................................................5-48
Headlamp Aiming...........................................5-49
Bulb Replacement..........................................5-49
Halogen Bulbs..............................................5-49
Headlamps..................................................5-50
Front Turn Signal, Sidemarker and
Parking Lamps..........................................5-51
Taillamps, Turn Signal, and Stoplamps............5-51
Back-Up Lamps............................................5-53
License Plate Lamp......................................5-53
Replacement Bulbs.......................................5-54
Windshield Wiper Blade Replacement..............5-54
Tires..............................................................5-57
Tire Sidewall Labeling...................................5-58
Tire Terminology and Denitions.....................5-61
Ination - Tire Pressure.................................5-64
Section 5 Service and Appearance Care
5-1

(e)Make sure the safety belt reminder light and safety
belt assemblies are working properly. Look for any
other loose or damaged safety belt system parts. If you
see anything that might keep a safety belt system
from doing its job, have it repaired. Have any torn or
frayed safety belts replaced. Also see Checking
the Restraint Systems on page 1-68.
(f)Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
rear compartment hinges, outer liftgate handle pivot
points, rear door detent link, roller mechanism, liftgate
handle pivot points, latch bolt, fuel door hinge, cargo
door hinge, locks, and folding seat hardware. More
frequent lubrication may be required when exposed to a
corrosive environment. Applying silicone grease on
weatherstrips with a clean cloth will make them
last longer, seal better, and not stick or squeak.
(g)Inspect hoses for cracks, chafing, leaks, kinks, and
proper installation.(h)Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police, or delivery
service.
(i)Drain, flush, and refill cooling system. This service
can be complex; you should have your dealer/retailer
perform this service. See Engine Coolant on page 5-26
for what to use. Inspect hoses. Clean radiator,
condenser, pressure cap, and filler neck. Pressure test
the cooling system and pressure cap.
(j)A fluid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the fluid level checked. Add fluid if needed.
(k)If you drive regularly under dusty conditions, inspect
the filter at each engine oil change.
(l)Visually inspect belt for fraying, excessive cracks, or
obvious damage. Replace belt if necessary.
6-8