2007 GMC ENVOY engine

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.
{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).
SeeFour-Wheel Drive on page 122for
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”
underFour-Wheel Drive on page 122.
358

If You Do Decide To Pull A Trailer
If you do, here are some important points:
There are many different laws, including speed
limit restrictions, having to do with trailering.
Make sure your rig will be legal, not only where
you live but also where you’ll be driving. A good
source for this information can be state or
provincial police.
Consider using a sway control. See “Hitches”
later in this section.
Don’t tow a trailer at all during the rst
500 miles (800 km) your new vehicle is driven.
Your engine, axle or other parts could be
damaged.
Then, during the rst 500 miles (800 km) that
you tow a trailer, don’t drive over 50 mph
(80 km/h) and don’t make starts at full throttle.
This helps your engine and other parts of your
vehicle wear in at the heavier loads.
You can tow in DRIVE (D). You may want to
shift the transmission to THIRD (3) or, if
necessary, a lower gear selection if the
transmission shifts too often (e.g., under heavy
loads and/or hilly conditions).Three important considerations have to do with
weight:
the weight of the trailer,
the weight of the trailer tongue
and the weight on your vehicle’s tires.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig.
For example, speed, altitude, road grades, outside
temperature and how much your vehicle is used
to pull a trailer are all important. It can also depend
on any special equipment that you have on your
vehicle, and the amount of tongue weight the
vehicle can carry. See “Weight of the Trailer
Tongue” later in this section for more information.
Maximum trailer weight is calculated assuming
only the driver is in the tow vehicle and it has all
the required trailering equipment. The weight
of additional optional equipment, passengers and
cargo in the tow vehicle must be subtracted
from the maximum trailer weight.
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Look in the following chart to nd the maximum trailer weight for your vehicle.
Vehicle Axle Ratio Max.Trailer Wt. *GCWR
2WD Envoy (L6 Engine)3.42 5,300 lbs. (2 404 kg) 10,000 lbs. (4 536 kg)
3.73 5,800 lbs. (2 631 kg) 10,500 lbs. (4 763 kg)
4.10 6,300 lbs. (2 858 kg) 11,000 lbs. (4 990 kg)
2WD Envoy (V8 Engine)3.42 6,100 lbs. (2 767 kg) 11,000 lbs. (4 990 kg)
3.73 6,600 lbs (2 994 kg) 11,500 lbs (5 216 kg)
4WD Envoy (L6 Engine)3.42 5,200 lbs. (2 359 kg) 10,000 lbs. (4 536 kg)
3.73 5,700 lbs. (2 858 kg) 10,500 lbs. (4 763 kg)
4.10 6,200 lbs. (2 812 kg) 11,000 lbs. (4 990 kg)
4WD Envoy (V8 Engine)3.42 6,000 lbs. (2 721 kg) 11,000 lbs. (4 990 kg)
3.73 6,500 lbs (2 948 kg) 11,500 lbs. (5 216 kg)
*The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded
vehicle and trailer including any passengers, cargo, equipment and conversion. The GCWR for your
vehicle should not be exceeded.
364

Driving with a Trailer
{CAUTION:
If you have a rear-most window open and
you pull a trailer with your vehicle, carbon
monoxide (CO) could come into your
vehicle. You can not see or smell CO. It can
cause unconsciousness or death. See
Engine Exhaust on page 131. To maximize
your safety when towing a trailer:
Have your exhaust system inspected
for leaks, and make necessary repairs
before starting on your trip.
Keep the rear-most windows closed.
If exhaust does come into your vehicle
through a window in the rear or another
opening, drive with your front, main
heating or cooling system on and with
the fan on any speed. This will bring
fresh, outside air into your vehicle.
CAUTION: (Continued)
CAUTION: (Continued)
Do not use the climate control setting for
maximum air because it only recirculates
the air inside your vehicle. SeeDual
Climate Control System on page 186.
Towing a trailer requires a certain amount of
experience. Before setting out for the open road,
you’ll want to get to know your rig. Acquaint
yourself with the feel of handling and braking with
the added weight of the trailer. And always
keep in mind that the vehicle you are driving is
now a good deal longer and not nearly as
responsive as your vehicle is by itself.
Before you start, check all trailer hitch parts and
attachments, safety chains, electrical connection,
lamps, tires and mirror adjustment. If the trailer
has electric brakes, start your vehicle and
trailer moving and then apply the trailer brake
controller by hand to be sure the brakes are
working. This lets you check your electrical
connection at the same time.
370

Turn Signals When Towing a Trailer
The arrows on your instrument panel will
ash whenever you signal a turn or lane change.
Properly hooked up, the trailer lamps will also
ash, telling other drivers you’re about to
turn, change lanes or stop.
When towing a trailer, the arrows on your
instrument panel will ash for turns even if the
bulbs on the trailer are burned out. Thus, you may
think drivers behind you are seeing your signal
when they are not. It’s important to check
occasionally to be sure the trailer bulbs are
still working.
Driving On Grades
Reduce speed and shift to a lower gearbefore
you start down a long or steep downgrade. If you
don’t shift down, you might have to use your
brakes so much that they would get hot and no
longer work well.
You can tow in DRIVE (D). You may want to shift
the transmission to THIRD (3) or a lower gear,
under heavy loads or hilly conditions.
When towing at high altitude on steep uphill
grades, consider the following: Engine coolant will
boil at a lower temperature than at normal
altitudes. If you turn your engine off immediately
after towing at high altitude on steep uphill grades,
your vehicle may show signs similar to engine
overheating. To avoid this, let the engine run while
parked (preferably on level ground) with the
automatic transmission in PARK (P) for a few
minutes before turning the engine off. If you do get
the overheat warning, seeEngine Overheating
on page 408.
372

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 122.
373

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.
374

Service........................................................ 380
Accessories and Modications................... 380
California Proposition 65 Warning.............. 381
Doing Your Own Service Work.................. 381
Adding Equipment to the Outside of
Your Vehicle.......................................... 382
Fuel............................................................. 382
Gasoline Octane........................................ 382
Gasoline Specications.............................. 383
California Fuel........................................... 383
Additives................................................... 383
Fuels in Foreign Countries........................ 384
Filling the Tank......................................... 385
Filling a Portable Fuel Container............... 387
Checking Things Under the Hood.............. 388
Hood Release........................................... 388
Engine Compartment Overview.................. 390
Engine Oil................................................. 394
Engine Oil Life System.............................. 398
Engine Air Cleaner/Filter............................ 400
Automatic Transmission Fluid.................... 401
Engine Coolant.......................................... 405Radiator Pressure Cap.............................. 408
Engine Overheating................................... 408
Cooling System......................................... 411
Engine Fan Noise..................................... 416
Power Steering Fluid ................................. 417
Windshield Washer Fluid........................... 418
Brakes...................................................... 419
Battery...................................................... 422
Jump Starting............................................ 423
Rear Axle.................................................... 428
Four-Wheel Drive........................................ 428
Front Axle................................................... 429
Bulb Replacement....................................... 430
Halogen Bulbs........................................... 430
Headlamps................................................ 431
Front Turn Signal, Sidemarker and
Parking Lamps....................................... 432
Taillamps, Turn Signal, and Stoplamps...... 432
Back-Up Lamps......................................... 434
License Plate Lamp................................... 435
Replacement Bulbs................................... 435
Section 5 Service and Appearance Care
377