2010 GMC SIERRA DENALI service

Towing
Towing Your Vehicle
To avoid damage, the disabled vehicle should be towed
with all four wheels off the ground. Consult your dealer/
retailer or a professional towing service if the disabled
vehicle must be towed. SeeRoadside Assistance
Program on page 8‑7.
To tow the vehicle behind another vehicle for
recreational purposes, such as behind a motorhome,
see “Recreational Vehicle Towing” following.
Recreational Vehicle Towing
Recreational vehicle towing means towing the vehicle
behind another vehicle–such as behind a motorhome.
The two most common types of recreational vehicle
towing are known as “dinghy towing”(towing the vehicle
with all four wheels on the ground) and “dolly towing”
(towing the vehicle with two wheels on the ground and
two wheels up on a device known as a “dolly”).Here are some important things to consider before
recreational vehicle towing:
.What is the towing capacity of the towing vehicle?
Be sure to read the tow vehicle manufacturer's
recommendations.
.What is the distance that will be travelled? Some
vehicles have restrictions on how far and how long
they can tow.
.Is the proper towing equipment going to be used?
See your dealer/retailer or trailering professional
for additional advice and equipment
recommendations.
.Is the vehicle ready to be towed? Just as preparing
the vehicle for a long trip, make sure the vehicle is
prepared to be towed. See
Before Leaving on a
Long Trip on page 5‑25.
5-38

All DIC warning and service messages must first be
acknowledged by the driver by pressing the odometer
trip stem or the DIC Vehicle Information button
(if equipped) before the Trailer Brake Display Page can
be displayed and Trailer Gain can be adjusted.
TRAILER GAIN–This setting is displayed anytime the
Trailer Brake Display Page is active. This setting can be
adjusted from 0.0 to 10.0 with either a trailer connected
or disconnected. To adjust the Trailer Gain, press one of
the Trailer Gain adjustment buttons located on the
Trailer Brake Control Panel. Press and hold a gain
button to cause the Trailer Gain to continuously adjust.
To turn the output to the trailer off, adjust the Trailer
Gain setting to 0.0 (zero).
0.0 (zero) gain is the factory default setting. To properly
adjust trailer gain, see the Trailer Gain Adjustment
Procedure later in this section.
TRAILER OUTPUT –This is displayed any time a trailer
with electric brakes is connected. Output to the electric
brakes is based on the amount of vehicle braking
present and relative to the Trailer Gain setting. Output is
displayed from 0 to 10 bars for each gain setting. The Trailer Output will indicate
“- - - - - -“on the Trailer
Brake Display Page whenever the following occur:
.No trailer is connected.
.A trailer without electric brakes is connected (no
DIC message is displayed).
.A trailer with electric brakes has become
disconnected (a CHECK TRAILER WIRING
message will also be displayed on the DIC).
.There is a fault present in the wiring to the electric
trailer brakes (a CHECK TRAILER WIRING
message will also be displayed on the DIC).
.There is a fault in the ITBC system (a SERVICE
TRAILER BRAKE SYSTEM message will also be
displayed in the DIC).
Manual Trailer Brake Apply
The Manual Trailer Brake Apply Lever is located on the
Trailer Brake Control Panel and is used to apply the
trailer ’s electric brakes independent of the vehicle’ s
brakes. This lever is used in the Trailer Gain Adjustment
Procedure to properly adjust the power output to the
trailer brakes. Sliding the lever to the left will apply only
the trailer brakes. The power output to the trailer is
indicated in the Trailer Brake Display Page in the DIC.
If the vehicle’s service brakes are applied while using
the Manual Trailer Brake Apply Lever, the trailer output
power will be the greater of the two.
5-52

To determine if the electrical fault is on the vehicle side
or trailer side of the trailer wiring harness connection,
do the following:1. Disconnect the trailer wiring harness from the vehicle.
2. Turn the ignition OFF.
3. Wait ten seconds, then turn the ignition back to RUN.
4. If the CHECK TRAILER WIRING message re-appears, the electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING message only
re-appears when connecting the trailer wiring
harness to the vehicle, the electrical fault is on the
trailer side.
SERVICE TRAILER BRAKE SYSTEM –This message
will be displayed when there is a problem with the ITBC
system. If this message persists over multiple ignition
cycles there is problem with the ITBC system. Take the
vehicle to an authorized GM dealer to have the ITBC
system diagnosed and repaired. If either the CHECK TRAILER WIRING or SERVICE
TRAILER BRAKE SYSTEM message is displayed while
driving the vehicle, power is no longer available to the
trailer brakes. When traffic conditions allow, carefully
pull the vehicle over to the side of the road and turn the
ignition off. Check the wiring connection to the trailer
and turn the ignition back on. If either of these
messages continues, either the vehicle or trailer needs
service.
An authorized GM dealer may be able to diagnose and
repair problems with the trailer. However, any diagnosis
and repair of the trailer is not covered under the vehicle
warranty. Please contact your trailer dealer for
assistance with trailer repairs and trailer warranty
information.
5-55

{WARNING:
It can be dangerous to get out of the vehicle if the
shift lever is not fully in P (Park) with the parking
brake firmly set. The vehicle can roll.
If the engine has been left running, the vehicle
can move suddenly. You or others could be
injured. To be sure the vehicle will not move, even
when on fairly level ground, always put the shift
lever fully in P (Park) with the parking brake
firmly set.
Leaving After Parking on a Hill
1. Apply and hold the brake pedal.
2. Start the engine
3. Shift into a gear
4. Release the parking brake
5. Let up on the brake pedal.
6. Drive slowly until the trailer is clear of the chocks.
7. Stop and have someone pick up and store thechocks.
Maintenance When Trailer Towing
The vehicle needs service more often when pulling a
trailer. See this manual's Maintenance Schedule or
Index for more information. Things that are especially
important in trailer operation are automatic transmission
fluid, engine oil, axle lubricant, belts, cooling system
and brake system. It is a good idea to inspect these
before and during the trip.
Check periodically to see that all hitch nuts and bolts
are tight.
5-59

Trailer Wiring Harness
Heavy-Duty Trailer Wiring Harness Package
The vehicle has a seven-pin universal heavy-duty trailer
connector attached to the rear bumper beam next to the
integrated trailer hitch.The seven-wire harness contains the following trailer
circuits:
.Yellow: Left Stop/Turn Signal
.Dark Green: Right Stop/Turn Signal
.Brown: Taillamps
.White: Ground
.Light Green: Back-up Lamps
.Red: Battery Feed*
.Dark Blue: Trailer Brake*
*The fuses for these two circuits are installed in the
underhood electrical center, but the wires are not
connected. They should be connected by your dealer/
retailer or a qualified service center.
If charging a remote (non-vehicle) battery, press the
tow/haul mode button located at the end of the shift
lever. This will boost the vehicle system voltage and
properly charge the battery. If the trailer is too light for
tow/haul mode, turn on the headlamps as a second way
to boost the vehicle system and charge the battery.
5-60

Electric Brake Control Wiring
Provisions
These wiring provisions are included with the vehicle as
part of the trailer wiring package. These provisions are
for an electric brake controller. The instrument panel
contains blunt cut wires near the data link connector for
the trailer brake controller. The harness contains the
following wires:
.Dark Blue: Brake Signal to Trailer Connector
.Red/Black: Battery
.Light Blue/White: Brake Switch
.White: Ground
It should be installed by your dealer/retailer or a
qualified service center.
If the vehicle is equipped with an ITBC, the blunt cuts
exist, but are not connected further in the harness. If an
aftermarket trailer brake controller is installed, the ITBC
must be disconnected. Do not power both ITBC and
aftermarket controllers to control the trailer brakes at the
same time.
Trailer Recommendations
Subtract the hitch loads from the Cargo Weight Rating
(CWR). CWR is the maximum weight of the load the
vehicle can carry. It does not include the weight of the
people inside, but you can figure about 150 lbs. (68 kg)
for each passenger. The total cargo load must not be
more than the vehicles CWR.
Weigh the vehicle with the trailer attached, so the
GVWR or GAWR are not exceeded. If using a
weight-distributing hitch, weigh the vehicle without the
spring bars in place.
The best performance is obtained by correctly
spreading out the weight of the load and choosing the
correct hitch and trailer brakes.
For more information see Towing a Trailer
on
page 5‑42.
5-61

Section 6 Service and Appearance Care
Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Accessories and Modifications . . . . . . . . . . . . . . . . . . 6-4
California Proposition 65 Warning . . . . . . . . . . . . . . . 6-5
California Perchlorate Materials Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Doing Your Own Service Work . . . . . . . . . . . . . . . . . . 6-5
Adding Equipment to the Outside of the Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
Gasoline Octane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Gasoline Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
California Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
Fuel E85 (85% Ethanol) . . . . . . . . . . . . . . . . . . . . . . . . . 6-9
Fuels in Foreign Countries . . . . . . . . . . . . . . . . . . . . . 6-10
Filling the Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
Filling a Portable Fuel Container . . . . . . . . . . . . . . . 6-13
Checking Things Under the Hood . . . . . . . . . . . . . . .6-14
Hood Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
Engine Compartment Overview . . . . . . . . . . . . . . . . 6-16
Engine Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-18
Engine Oil Life System . . . . . . . . . . . . . . . . . . . . . . . . 6-20
Engine Air Cleaner/Filter . . . . . . . . . . . . . . . . . . . . . . . 6-22
Automatic Transmission Fluid . . . . . . . . . . . . . . . . . . 6-24
Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28 Engine Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-29
Engine Overheating . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34
Overheated Engine Protection
Operating Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-37
Engine Fan Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-37
Power Steering Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . 6-38
Windshield Washer Fluid . . . . . . . . . . . . . . . . . . . . . . 6-39
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-40
Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-43
Jump Starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-44
All-Wheel Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-49
Rear Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-50
Front Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-51
Headlamp Aiming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-52
Bulb Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-55
Halogen Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-55
Headlamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-55
Center High-Mounted Stoplamp (CHMSL) and Cargo Lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-57
Taillamps, Turn Signal, Stoplamps and Back-up Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-58
License Plate Lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-60
Replacement Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-60
Windshield Wiper Blade Replacement . . . . . . . . . . .6-61
6-1

Section 6 Service and Appearance Care
Tires. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-62
Tire Sidewall Labeling . . . . . . . . . . . . . . . . . . . . . . . . . 6-63
Tire Terminology and Definitions . . . . . . . . . . . . . . . 6-68
Inflation - Tire Pressure . . . . . . . . . . . . . . . . . . . . . . . . 6-71
High-Speed Operation . . . . . . . . . . . . . . . . . . . . . . . . . 6-72
Tire Pressure Monitor System . . . . . . . . . . . . . . . . . 6-73
Tire Pressure Monitor Operation . . . . . . . . . . . . . . . 6-74
Tire Inspection and Rotation . . . . . . . . . . . . . . . . . . . 6-78
When It Is Time for New Tires . . . . . . . . . . . . . . . . . 6-79
Buying New Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-80
Different Size Tires and Wheels . . . . . . . . . . . . . . . 6-82
Uniform Tire Quality Grading . . . . . . . . . . . . . . . . . . . 6-82
Wheel Alignment and Tire Balance . . . . . . . . . . . . 6-84
Wheel Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-84
Tire Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-85
If a Tire Goes Flat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-85
Changing a Flat Tire . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-86
Removing the Spare Tire and Tools . . . . . . . . . . . . 6-88
Removing the Flat Tire and Installing the Spare Tire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-92
Secondary Latch System . . . . . . . . . . . . . . . . . . . . . . 6-97
Storing a Flat or Spare Tire and Tools . . . . . . . . 6-100
Spare Tire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-104 Appearance Care
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-105
Interior Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-105
Fabric/Carpet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-106
Leather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-107
Instrument Panel, Vinyl, and Other Plastic Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-107
Wood Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-108
Care of Safety Belts . . . . . . . . . . . . . . . . . . . . . . . . . . 6-108
Weatherstrips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-108
Washing Your Vehicle . . . . . . . . . . . . . . . . . . . . . . . . 6-108
Cleaning Exterior Lamps/Lenses . . . . . . . . . . . . . 6-109
Finish Care . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-109
Windshield and Wiper Blades . . . . . . . . . . . . . . . . . 6-110
Aluminum or Chrome-Plated Wheels and Trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-110
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-111
Sheet Metal Damage . . . . . . . . . . . . . . . . . . . . . . . . . 6-111
Finish Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-112
Underbody Maintenance . . . . . . . . . . . . . . . . . . . . . . 6-112
Chemical Paint Spotting . . . . . . . . . . . . . . . . . . . . . . 6-112
6-2