2005 GMC YUKON DENALI towing

Trailer Wiring Harness
Heavy-Duty Trailer Wiring Package
Your vehicle is equipped with the seven-wire trailer
towing harness. This harness with a seven-pin universal
heavy-duty trailer connector is attached to a bracket
on the hitch platform.
The Center High-Mounted Stoplamp (CHMSL) wire is tied
next to the trailer wiring harness for use with a trailer.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
**If you are charging a remote (non-vehicle) battery,
turn on the headlamps to boost the vehicle system
voltage and properly charge the battery.
4-62

Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission uid
level is when the engine oil is changed.
Change both the uid and lter every 50,000 miles
(83 000 km) if the vehicle’s GVWR is over 8,600 lbs
(3 901 kg) or 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.
If your vehicle’s GVWR is not over 8,600 lbs (3 901 kg)
and you do not use your vehicle under any of these
conditions, change the uid and lter every
100,000 miles (166 000 km).
SeeScheduled Maintenance on page 6-4.
How to Check
Because this operation can be a little difficult, you may
choose to have this done at the dealership service
department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little uid can damage
your transmission. Too much can mean that some
of the uid could come out and fall on hot engine
part or exhaust system parts, starting a re.
Too little uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission uid.
Wait at least 30 minutes before checking the
transmission uid level if you have been driving:
When outside temperatures are above 90°F (32°C).
At high speed for quite a while.
In heavy traffic — especially in hot weather.
While pulling a trailer.
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).
5-22

If No Steam Is Coming From Your
Engine
An overheat warning, along with a low coolant condition,
can indicate a serious problem.
If you get an engine overheat warning, but see or hear
no steam, the problem may not be too serious.
Sometimes the engine can get a little too hot when you:
Climb a long hill on a hot day.
Stop after high-speed driving.
Idle for long periods in traffic.
Tow a trailer. SeeTowing a Trailer on page 4-52.
If you get the overheat warning with no sign of steam, try
this for a minute or so:
1. If your air conditioner is on, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
3. If you are in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving — DRIVE (D).If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there is still no sign of steam and your vehicle is
equipped with an engine-driven cooling fan, push down
the accelerator until the engine speed is about twice
as fast as normal idle speed for at least three minutes
while you are parked.
If there is still no sign of steam and your vehicle is
equipped with an electric engine cooling fan, idle the
engine for three minutes while you are parked.
If you still have the warning,turn off the engine and get
everyone out of the vehicleuntil it cools down. Also,
see “Overheated Engine Protection Operating Mode”
later in this section.
You may decide not to lift the hood but to get service
help right away.
5-29

Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
REDUCED ENGINE POWER message is displayed, an
overheat protection mode which alternates ring
groups of cylinders helps prevent engine damage. In
this mode, you will notice a loss in power and engine
performance. This operating mode allows your vehicle to
be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair the
cause of coolant loss, change the oil and reset the oil
life system. SeeEngine Oil on page 5-14.
Cooling System
When you decide it is safe to lift the hood, here is what
you will see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Electric Engine Cooling Fan (If Equipped)
5-30

Engine Fan Noise
If your vehicle is equipped with a clutched engine
cooling fan, when the clutch is engaged, the fan spins
faster to provide more air to cool the engine. In
most everyday driving conditions, the fan is spinning
slower and the clutch is not fully engaged. This improves
fuel economy and reduces fan noise. Under heavy
vehicle loading, trailer towing, and/or high outside
temperatures, the fan speed increases as the clutch
more fully engages, so you may hear an increase in fan
noise. This is normal and should not be mistaken as
the transmission slipping or making extra shifts. It
is merely the cooling system functioning properly. The
fan will slow down when additional cooling is not
required and the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If your vehicle is equipped with electric cooling fans, you
may hear the fans spinning at low speed during most
everyday driving. The fans may turn off if no cooling is
required. Under heavy vehicle loading, trailer towing,
and/or high outside temperatures, or if you are operating
your air conditioning system, the fans change to high
speed and you may hear an increase in fan noise. This
is normal and indicates that the cooling system is
functioning properly. The fans will change to low speed
when additional cooling is no longer required.
Power Steering Fluid
SeeEngine Compartment Overview on page 5-12for
power steering uid reservoir location.
5-35

(c)Visually inspect hoses and have them replaced if they
are cracked, swollen or deteriorated. Inspect all pipes,
ttings and clamps; replace with genuine GM parts as
needed. To help ensure proper operation, a pressure test
of the cooling system and pressure cap and cleaning the
outside of the radiator and air conditioning condenser is
recommended at least once a year.
(d)Visually inspect wiper blades for wear or cracking.
Replace blade inserts that appear worn or damaged
or that streak or miss areas of the windshield.
(e)Make sure the safety belt reminder light and all your
belts, buckles, latch plates, retractors and anchorages
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 look for any opened or broken airbag
coverings, and have them repaired or replaced.
(The airbag system does not need regular maintenance.)
(f)Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
door hinges, liftgate hinge, liftgate linkage, liftgate handle
pivot points, latch bolt, fuel 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 system. Check all fuel and vapor lines and
hoses for proper hook-up, routing and condition.
Check that the purge valve works properly (if equipped).
Replace as needed.
(h)Change automatic transmission uid and lter 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, ush and rell cooling system. This service
can be complex; you should have your dealer perform
this service. See Engine Coolant on page 5-25 for
what to use. Inspect hoses. Clean radiator, condenser,
pressure cap and ller neck. Pressure test the cooling
system and pressure cap.
(j)A uid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the uid level checked. Add uid if needed.
(k)If you drive regularly under dusty conditions, inspect
the lter at each engine oil change.
6-8

Power (cont.)
Lumbar Controls........................................... 1-4
Retained Accessory (RAP)............................2-20
Seat............................................................ 1-3
Steering Fluid.............................................5-35
Windows....................................................2-16
Programmable Automatic Door Locks.................2-10
Programming the HomeLink
®Transmitter...........2-39
Puddle Lamps................................................3-16
Q
Questions and Answers About Safety Belts.........1-31
R
Radios..........................................................3-67
Care of Your Cassette Tape Player...............3-100
Care of Your CD and DVD Player................3-102
Care of Your CD Player..............................3-101
Care of Your CDs and DVDs.......................3-101
CD Changer...............................................3-96
Navigation/Radio System..............................3-94
Radio with Cassette and CD.........................3-68
Rear Seat Audio..........................................3-94
Setting the Time..........................................3-68Radios (cont.)
Theft-Deterrent............................................3-99
Understanding Reception............................3-100
Reading Lamps..............................................3-18
Rear Axle......................................................5-48
Rear Climate Control System............................3-26
Rear Door Security Locks................................2-12
Rear Heated Seats........................................... 1-9
Rear Safety Belt Comfort Guides......................1-44
Rear Seat Audio (RSA)....................................3-94
Rear Seat Entertainment System.......................3-83
Rear Seat Operation......................................... 1-8
Rear Seat Passengers, Safety Belts..................1-41
Rear Storage Area..........................................2-45
Rearview Mirror, Automatic Dimming
with OnStar
®, Compass and Temperature
Display......................................................2-32
Reclining Seatbacks.......................................... 1-6
Recommended Fluids and Lubricants.................6-12
Recovery Hooks.............................................4-43
Recreational Vehicle Towing.............................4-50
Remote Keyless Entry System............................ 2-5
Remote Keyless Entry System, Operation............ 2-6
Removing the Flat Tire and Installing
the Spare Tire.............................................5-80
Removing the Spare Tire and Tools...................5-76
Replacement Bulbs.........................................5-54
10

Tires.............................................................5-56
Aluminum Wheels, Cleaning........................5-100
Buying New Tires........................................5-68
Chains.......................................................5-73
Changing a Flat Tire....................................5-74
Cleaning...................................................5-101
If a Tire Goes Flat.......................................5-74
Ination -- Tire Pressure...............................5-62
Inspection and Rotation................................5-66
Installing the Spare Tire................................5-80
Pressure Monitor System..............................5-63
Removing the Flat Tire.................................5-80
Removing the Spare Tire and Tools...............5-76
Secondary Latch System..............................5-86
Spare Tire..................................................5-94
Storing a Flat or Spare Tire and Tools............5-90
Tire Sidewall Labelling..................................5-57
Tire Terminology and Denitions....................5-60
Uniform Tire Quality Grading.........................5-70
Wheel Alignment and Tire Balance.................5-71
Wheel Replacement.....................................5-72
When It Is Time for New Tires......................5-68
Top Strap......................................................1-57
Top Strap Anchor Location...............................1-58
Tow/Haul Mode...............................................2-26
Tow/Haul Mode Light.......................................3-44
Towing
Recreational Vehicle.....................................4-50Towing (cont.)
Towing a Trailer..........................................4-52
Your Vehicle...............................................4-50
Traction
Off Light.....................................................3-36
StabiliTrak
®System....................................... 4-8
Trailer
Recommendations.......................................4-51
Transmission
Fluid, Automatic...........................................5-22
Temperature Gage.......................................3-37
Transmission Operation, Automatic....................2-24
Turn and Lane-Change Signals.......................... 3-8
Turn Signal/Multifunction Lever........................... 3-7
U
Understanding Radio Reception.......................3-100
Uniform Tire Quality Grading............................5-70
V
Vehicle
Control........................................................ 4-5
Damage Warnings........................................... iv
Symbols......................................................... iv
Vehicle Customization, DIC..............................3-61
13