ECU GMC SIERRA 2008 Repair Manual

You must weigh any accessories or other
equipment that you add to your vehicle. Then,
subtract this extra weight from the CWR. This extra
weight may shorten the center of gravity zone of
your vehicle. Your dealer can help you with this.
If your slide-in camper and its load weighs
less than the CWR, the center of gravity zone for
your vehicle may be larger.
Your dealer can help you make a good
vehicle-camper match and help you determine the
CWR.
After you have loaded your vehicle and camper,
drive to a weigh station and weigh the front
and rear wheels separately. This will tell you the
loads on the axles. The loads on the front and rear
axles should not be more than either of the
Gross Axle Weight Ratings (GAWR). The total of
the axle loads should not be more than the
Gross Vehicle Weight Rating (GVWR).
Open the driver’s door and look at the
Certication/Tire label to nd out your vehicle’s
GAWRs and GVWR.
If your vehicle has gone over the weight ratings,
move or take out some things until all the
weight falls below the ratings.Secure loose items to prevent weight shifts that
could affect the balance of your vehicle. When the
truck-camper is loaded, drive to a scale and weigh
on the front and on the rear wheels separately to
determine axle loads. Individual axle loads should
not exceed either of the gross axle weight ratings
(GAWR). The total axle loads should not exceed
your vehicle’s gross vehicle weight rating (GVWR).
These ratings are given on the vehicle certication
label attached to the rear edge of the driver’s door.
See “Certication/Tire Label” underLoading Your
Vehicle on page 4-36. If weight ratings are
exceeded, move or remove items to bring all
weights below the ratings.
When you install and load your slide-in camper,
check the manufacturer’s instructions.
If you want more information on curb weights,
cargo weights, Cargo Weight Rating and the
correct center of gravity zone for your vehicle, your
dealer can help you. Just ask for a copy of
“Consumer Information, Truck-Camper Loading.”
4-49

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. See
Four-Wheel Drive on page 2-36for the proper
procedure to select the neutral 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 to LOCK/OFF.
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.
Two-wheel-drive vehicles should not be towed with the
rear wheels on the ground. Two-wheel-drive
transmissions have no provisions for internal lubrication
while being towed.
To dolly tow a two-wheel-drive vehicle, you must tow
the vehicle with the rear wheels on the dolly. See “Rear
Towing (Rear Wheels Off the Ground)” later in this
section for more information.
4-52

Four-Wheel-Drive Vehicles
Use the following procedure to tow your vehicle:
1. Drive the vehicle up onto the tow dolly.
2. Shift the 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
tow 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. See
Four-Wheel Drive on page 2-36for the proper
procedure to select the neutral 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 to LOCK/OFF.
4-53

Rear Towing (Rear Wheels Off the
Ground)
Two-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 2-49.
3. Put the transmission in PARK (P).
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. Make sure
the wheels are straight before towing.
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 tow vehicle.
6. Turn the ignition to LOCK/OFF.
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 2-49.
3. Put the transmission in PARK (P).
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.
{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. See
Four-Wheel Drive on page 2-36.
4-54

K-3500 Extended
Cab (4WD)* Axle RatioMaximum Trailer Weight GCWR**
6.0L V83.73
4.109,500 lbs (4 309 kg)
12,000 lbs (5 443 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
6.0L V8
(Dual Rear Wheels)3.73
4.109,200 lbs (4 173 kg)
11,700 lbs (5 307 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
*Fifth-wheel or gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to
3,500 lbs (1 587 kg) maximum.
*Trailer rating limited to 13,000 lbs (5 897 kg) with weight distributing hitch.
**The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and
trailer including any passengers, cargo, equipment and conversions. The GCWR for your vehicle should not be
exceeded.
K-3500 Crew
Cab (4WD)*Axle Ratio Maximum Trailer Weight GCWR**
6.0L V83.73
4.109,300 lbs (4 218 kg)
11,800 lbs (5 352 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
6.0L V8
(Dual Rear Wheels)3.73
4.109,100 lbs (4 128 kg)
11,600 lbs (5 262 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
*Fifth-wheel or gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to
3,500 lbs (1 587 kg) maximum.
*Trailer rating limited to 13,000 lbs (5 897 kg) with weight distributing hitch.
**The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and
trailer including any passengers, cargo, equipment and conversions. The GCWR for your vehicle should not be
exceeded.
Ask your dealer/retailer for our trailering information or
advice, or write us at our Customer Assistance Offices.SeeCustomer Assistance Offices on page 7-5for more
information.
4-72

Before you start, check all trailer hitch parts and
attachments, safety chains, electrical connector, 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.
During your trip, check occasionally to be sure that the
load is secure, and that the lamps and any trailer
brakes are still working.
While towing a trailer or when exposed to long periods
of sunshine, the oor of the truck bed may become
very warm. Avoid putting items in the truck bed
that might be affected by high ambient temperatures.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would when driving your vehicle without a trailer.
This can help you avoid situations that require
heavy braking and sudden turns.
Passing
You’ll need more passing distance up ahead when
you’re towing a trailer. And, because you’re a good deal
longer, you’ll need to go much farther beyond the
passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, just move that hand
to the left. To move the trailer to the right, move your
hand to the right. Always back up slowly and, if possible,
have someone guide you.
Making Turns
Notice:Making very sharp turns while trailering
could cause the trailer to come in contact with the
vehicle. Your vehicle could be damaged. Avoid
making very sharp turns while trailering.
When you’re turning with a trailer, make wider turns
than normal. Do this so your trailer won’t strike
soft shoulders, curbs, road signs, trees or other objects.
Avoid jerky or sudden maneuvers. Signal well in
advance.
4-87

Adding Coolant
If you need more coolant, add the proper DEX-COOL®
coolant mixture at the surge tank, but only when the
engine is cool. SeeCooling System on page 5-34
for more information.
{CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol,
and it will burn if the engine parts are hot
enough. Do not spill coolant on a hot engine.
When replacing the pressure cap, make sure it is
hand-tight and fully seated.
Coolant Surge Tank Pressure Cap
Notice:If the pressure cap is not tightly installed,
coolant loss and possible engine damage may
occur. Be sure the cap is properly and tightly
secured.
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. SeeEngine
Compartment Overview on page 5-14for more
information on location.
Engine Overheating
If your vehicle has the DURAMAX®Diesel engine, see
the DURAMAX®Diesel manual for more information.
You will nd a coolant temperature gage on your
vehicle’s instrument panel. SeeEngine Coolant
Temperature Gage on page 3-46.
In addition, you will nd ENGINE OVERHEATED STOP
ENGINE, ENGINE OVERHEATED IDLE ENGINE,
and ENGINE POWER IS REDUCED messages in the
Driver Information Center (DIC) on the instrument panel.
SeeDIC Warnings and Messages on page 3-63.
5-30

Headlamps
To replace one of these bulbs:
1. Open the hood. SeeHood Release on page 5-13
for more information.
2. If you are replacing the bulb on the passenger side
remove the Engine Air Cleaner cover. SeeEngine
Air Cleaner/Filter (Gasoline Engines) on page 5-19
for more information.
3. Reach in and access the bulb sockets from inside
the engine compartment.
4. Turn the bulb socket counterclockwise to remove it
from the headlamp assembly and pull it straight out.
5. Unplug the electrical connector from the old bulb by
releasing the clips on the bulb socket.
6. Replace it with a new bulb socket.
7. Plug in the electrical connector to the new
bulb socket.
8. Reinstall the new bulb socket into the headlamp
assembly and turn it clockwise to secure.
9. Close the hood.
5-60

If your vehicle has dual
rear wheels and the
tread design for the front
tires is different from the
dual rear tires, always
use the correct rotation
pattern shown here
when rotating the tires.
The dual tires are rotated as a pair, and the inside
rear tires become the outside rear tires.
When you install dual wheels, be sure the vent
holes in the inner and outer wheels on each side
are lined up.
After the tires have been rotated, adjust the front
and rear ination pressures as shown on the Tire
and Loading Information label. SeeInflation - Tire
Pressure on page 5-74andLoading Your Vehicle
on page 4-36.
Make certain that all wheel nuts are properly
tightened. See “Wheel Nut Torque” under
Capacities and Specifications on page 5-130.
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make wheel nuts
become loose after time. The wheel could
come off and cause an accident. When
you change a wheel, remove any rust or
dirt from places where the wheel attaches
to the vehicle. In an emergency, you can
use a cloth or a paper towel to do this;
but be sure to use a scraper or wire brush
later, if needed, to get all the rust or dirt
off. SeeChanging a Flat Tire on page 5-92.
If your vehicle has a Tire Pressure Monitor
System (TPMS), reset the TPMS sensors after
rotating the tires. SeeTire Pressure Monitor
Operation on page 5-78.
Make sure the spare tire, if your vehicle has one,
is stored securely. Push, pull, and then try to
rotate or turn the tire. If it moves, tighten the
cable. SeeStoring a Flat or Spare Tire and Tools
on page 5-108.
5-83

Tire Chains
{CAUTION:
If your vehicle has dual wheels or P265/65R18,
P275/55R20 or LT265/70R17 size tires, do not
use tire chains. They can damage your vehicle
because 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
CAUTION: (Continued)
CAUTION: (Continued)
vehicle, drive slowly, readjust, or remove the
device if it is contacting your vehicle, and do
not spin your vehicle’s wheels.
If you do nd traction devices that will t,
install them on the rear tires.
Notice:If your vehicle does not have dual wheels
and has a tire size other than P265/65R18,
P275/55R20 or LT265/70R17, use tire chains only
where legal and only when you must. Use chains
that are the proper size for your tires. Install them on
the tires of the rear axle. Do not use chains on the
tires of the front axle. Tighten them as tightly as
possible with the ends securely fastened. Drive
slowly and follow the chain manufacturer’s
instructions. If you can hear the chains contacting
your vehicle, stop and retighten them. If the contact
continues, slow down until it stops. Driving too
fast or spinning the wheels with chains on will
damage your vehicle.
5-90