brake GMC YUKON XL 2007 Repair Manual

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, belts, 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.
Trailer Wiring Harness
Your vehicle is equipped with the following wiring
harnesses for towing a trailer.
Basic Trailer Wiring
The trailer wiring harness, with a seven-pin
connector, is located at the rear of the vehicle and
is tied to the vehicle’s frame. The harness
connector can be plugged into a seven-pin
universal heavy-duty trailer connector available
through your dealer.
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 or a qualied service center.
420

Heavy-Duty Trailer Wiring Harness
Package
Your vehicle is equipped with the seven-wire
trailer towing harness. This harness with a
seven-pin universal trailer connector is attached to
a bracket on the hitch platform.
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 or a qualied service center.
If you are 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, you
can turn on the headlamps as a second way to
boost the vehicle system and charge the battery.
421

Electric Brake Control Wiring
Provisions
These wiring provisions are included with your
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 or a qualied
service center.
Power Winches
If you wish to use a power winch on your vehicle,
only use it when your vehicle is stationary or
anchored.
Trailer Recommendations
You must subtract your hitch loads from the Cargo
Weight Rating (CWR) for your vehicle. CWR is
the maximum weight of the load your vehicle can
carry. It doesn’t include the weight of the people
inside. But you can gure about 150 lbs. (68 kg) for
each seat. The total cargo load must not be
more than your vehicle’s CWR.
Weigh your vehicle with the trailer attached, so
that you won’t go over the GVWR or GAWR. If you
are using a weight-distributing hitch, weigh the
vehicle without the spring bars in place.
You’ll get the best performance if you spread out
the weight of your load the right way, and if
you choose the correct hitch and trailer brakes.
For more information, seeTowing a Trailer
on page 405.
422

Service.........................................................426
Accessories and Modications....................426
California Proposition 65 Warning...............427
Doing Your Own Service Work...................427
Adding Equipment to the Outside of
Your Vehicle...........................................428
Fuel..............................................................428
Gasoline Octane........................................428
Gasoline Specications...............................428
California Fuel............................................429
Additives....................................................429
Fuel E85 (85% Ethanol).............................430
Fuels in Foreign Countries.........................431
Filling the Tank..........................................432
Filling a Portable Fuel Container................434
Checking Things Under the Hood..............434
Hood Release............................................435
Engine Compartment Overview...................436
Engine Oil..................................................438
Engine Oil Life System...............................441
Engine Air Cleaner/Filter.............................443
Automatic Transmission Fluid.....................445
Engine Coolant...........................................449Coolant Surge Tank Pressure Cap.............451
Engine Overheating....................................452
Overheated Engine Protection
Operating Mode......................................454
Cooling System..........................................455
Engine Fan Noise......................................460
Power Steering Fluid..................................461
Windshield Washer Fluid............................462
Brakes.......................................................463
Battery.......................................................466
Jump Starting.............................................467
Rear Axle.....................................................472
Four-Wheel Drive.........................................473
Front Axle....................................................474
Headlamp Aiming........................................475
Bulb Replacement........................................478
Halogen Bulbs............................................478
Taillamps, Turn Signal, Stoplamps and
Back-up Lamps.......................................478
License Plate Lamp....................................480
Replacement Bulbs....................................481
Section 5 Service and Appearance Care
423

Service
Your dealer knows your vehicle best and wants
you to be happy with it. We hope you will go
to your dealer for all your service needs. You will
get genuine GM parts and GM-trained and
supported service people.
We hope you will want to keep your GM vehicle
all GM. Genuine GM parts have one of
these marks:
Accessories and Modications
When you add non-GM accessories to your vehicle
they can affect your vehicle’s performance and
safety, including such things as, airbags, braking,
stability, ride and handling, emissions systems,
aerodynamics, durability, and electronic systems
like anti-lock brakes, traction control and
stability control. Some of these accessories may
even cause malfunction or damage not covered by
warranty.
GM Accessories are designed to complement and
function with other systems on your vehicle.
Your GM dealer can accessorize your vehicle
using genuine GM Accessories. When you go to
your GM dealer and ask for GM Accessories,
you will know that GM-trained and supported
service technicians will perform the work using
genuine GM Accessories.
426

Filling a Portable Fuel Container
{CAUTION:
Never ll a portable fuel container while it
is in your vehicle. Static electricity
discharge from the container can ignite the
gasoline vapor. You can be badly burned
and your vehicle damaged if this occurs.
To help avoid injury to you and others:
Dispense gasoline only into approved
containers.
Do not ll a container while it is inside a
vehicle, in a vehicle’s trunk, pickup
bed, or on any surface other than the
ground.
Bring the ll nozzle in contact with the
inside of the ll opening before
operating the nozzle. Contact should
be maintained until the lling is
complete.
Do not smoke while pumping gasoline.
Checking Things Under
the Hood
{CAUTION:
An electric fan under the hood can start up
and injure you even when the engine is not
running. Keep hands, clothing, and tools
away from any underhood electric fan.
{CAUTION:
Things that burn can get on hot engine
parts and start a re. These include
liquids like fuel, oil, coolant, brake uid,
windshield washer and other uids, and
plastic or rubber. You or others could be
burned. Be careful not to drop or spill
things that will burn onto a hot engine.
434

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 443.
B. Air Filter Restriction Indicator (If Equipped).
SeeEngine Air Cleaner/Filter on page 443.
C. Coolant Surge Tank and Pressure Cap.
SeeCooling System on page 455andCoolant
Surge Tank Pressure Cap on page 451.
D. Remote Positive (+) Terminal. SeeJump
Starting on page 467.
E. Battery. SeeBattery on page 466.
F. Engine Oil Fill Cap. See “When to Add Engine
Oil” underEngine Oil on page 438.
G. Automatic Transmission Dipstick. See
“Checking the Fluid Level” underAutomatic
Transmission Fluid on page 445.H. Remote Negative (−) Terminal (Out of View).
SeeJump Starting on page 467.
I. Engine Oil Dipstick (Out of View). See
“Checking Engine Oil” underEngine Oil on
page 438.
J. Engine Cooling Fan. SeeCooling System on
page 455.
K. Power Steering Fluid Reservoir. SeePower
Steering Fluid on page 461.
L. Brake Master Cylinder Reservoir. See “Brake
Fluid” underBrakes on page 463.
M. Underhood Fuse Block. SeeUnderhood Fuse
Block on page 543.
N. Windshield Washer Fluid Reservoir. See
“Adding Washer Fluid” underWindshield
Washer Fluid on page 462.
437

To get the right reading, the uid should be at
normal operating temperature, which is 180°F to
200°F (82°C to 93°C).
Get the vehicle warmed up by driving about
15 miles (24 km) when outside temperatures are
above 50°F (10°C). If it is colder than 50°F (10°C),
drive the vehicle in THIRD (3) until the engine
temperature gage moves and then remains steady
for 10 minutes.
A cold uid check can be made after the vehicle
has been sitting for eight hours or more with
the engine off, but this is used only as a reference.
Let the engine run at idle for ve minutes if
outside temperatures are 50°F (10°C) or more. If it
is colder than 50°F (10°C), you may have to idle
the engine longer. Should the uid level be
low during this cold check, you must check the
uid hot before adding uid. Checking the uid hot
will give you a more accurate reading of the
uid level.Checking the Fluid Level
Prepare your vehicle as follows:
1. Park your vehicle on a level place. Keep the
engine running.
2. With the parking brake applied, place the shift
lever in PARK (P).
3. With your foot on the brake pedal, move the
shift lever through each gear range, pausing
for about three seconds in each range.
Then, position the shift lever in PARK (P).
4. Let the engine run at idle for three minutes
or more.
446

Brakes
Brake Fluid
Your brake master
cylinder reservoir is
lled with DOT-3 brake
uid. SeeEngine
Compartment Overview
on page 436for the
location of the reservoir.
There are only two reasons why the brake uid
level in the reservoir might go down. The rst
is that the brake uid goes down to an acceptable
level during normal brake lining wear. When
new linings are put in, the uid level goes back
up. The other reason is that uid is leaking out of
the brake system. If it is, you should have your
brake system xed, since a leak means that
sooner or later your brakes will not work well, or
will not work at all.So, it is not a good idea to top off your brake uid.
Adding brake uid will not correct a leak. If you
add uid when your linings are worn, then you will
have too much uid when you get new brake
linings. You should add or remove brake uid, as
necessary, only when work is done on the
brake hydraulic system.
{CAUTION:
If you have too much brake uid, it can
spill on the engine. The uid will burn if
the engine is hot enough. You or others
could be burned, and your vehicle could
be damaged. Add brake uid only when
work is done on the brake hydraulic
system. See “Checking Brake Fluid” in
this section.
When the brake uid falls to a low level, the brake
warning light will come on. SeeBrake System
Warning Light on page 232.
Refer to the Maintenance Schedule to determine
when to check your brake uid. SeeScheduled
Maintenance on page 555.
463

Checking Brake Fluid
You can check the brake uid without taking off
the cap.
Look at the brake uid
reservoir. The uid level
should be above
MIN. If it is not, have
your brake system
checked to see if there
is a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not
over the MAX mark.
What to Add
When you do need brake uid, use only DOT-3
brake uid. Use new brake uid from a sealed
container only. SeeRecommended Fluids
and Lubricants on page 564.Always clean the brake uid reservoir cap and the
area around the cap before removing it. This
will help keep dirt from entering the reservoir.
{CAUTION:
With the wrong kind of uid in your brake
system, your brakes may not work well, or
they may not even work at all. This could
cause a crash. Always use the proper
brake uid.
Notice:
Using the wrong uid can badly damage
brake system parts. For example, just a
few drops of mineral-based oil, such
as engine oil, in your brake system can
damage brake system parts so badly that
they will have to be replaced. Do not
let someone put in the wrong kind of uid.
If you spill brake uid on your vehicle’s
painted surfaces, the paint nish can
be damaged. Be careful not to spill brake
uid on your vehicle. If you do, wash it
off immediately. SeeWashing Your Vehicle
on page 532.
464