2003 GMC YUKON DENALI towing

Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission fluid
level is when the engine oil is changed.
Change both the fluid and filter every
50,000 miles
(83
000 km) if the vehicle’s GVWR is over 8,600 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.
0 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 and you do
not use your vehicle under any of these conditions,
change the fluid and filter every
100,000 miles
(1 66 000 km).
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 fluid can damage
your transmission. Too much can mean that some of the fluid could come out and fall
on hot engine
part or exhaust system parts, starting a fire.
Too little fluid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission fluid.
Wait at least 30 minutes before checking the
transmission fluid 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.
See
Part A: Scheduled Maintenance Services on
page 6-4.
5-20

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.
1 “J can be burned if you sb... coolant on hot
engine parts. Coolant contains ethylene glycol, and
it will burn if the engine parts are hot
enough. Don’t spill coolant on a hot engine.
When replacing the pressure cap, make sure it is
hand-tight.
Coolant Surge Tank Pressure Cap
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. See Engine
Compartment Overview on page
5-12 for more
information on location.
Notice: Your pressure cap is a pressure-type cap
and must be tightly installed to prevent coolant
loss
and possible engine damage from overheating.
See “Capacities and Specifications” for more
information.
Engine Overheating
You will find a coolant temperature gage on your
vehicle’s instrument panel. See Engine Coolant
Temperature Gage
on page 3-36. in addition, yoti ill
find a LOW COOLANT, ENGINE COOLANT HOT,
ENGINE OVERHEATED and a REDUCED ENGINE
POWER message in the DIC on the instrument panel.
See DIC Warnings and Messages on page
3-52.
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 firing
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. See “Engine Oil” in the Index.
5-25

If No Steam Is Coming From Your
Engine
An overheat warning, along with a low coolant message,
can indicate a serious problem. See
Low Coolant
Level Warning Message under DIC Warnings and
Messages
on page 3-52.
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:
0 Climb a long hill on a hot day.
Stop after high-speed driving.
0 Idle for long periods in traffic.
0 Tow a trailer. See Towing a Trailer on page 4-47.
If you get the overheat warning with no sign of steam, try
this for a minute or so:
1. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
If you no longer have the overheat warning, you can
drive. Just
to be safe, drive slower for about 10 minutes.
If the warning doesn’t come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there’s still no sign of steam, push down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you’re parked. If you still have the warning, turn
off the
engine and get everyone out
of the vehicle until it
cools down. Also, see “Overheated Engine Protection
Operating Mode” listed previously in this section.
You may decide not
to lift the hood but to get service
help right away.
2. If you’re in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
- DRIVE (D).
5-27

4. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the
engine cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level
is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches
FULL COLD mark.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When
the clutch
is engaged, the fan spins faster to provide
more air
tu 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.
5-33

37,500 Miles (62 500 km)
U Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-56 for proper rotation pattern and additional
information. (See footnote
+.)
U Rotate tires. See Tire inspection and Rotation on
45,000 Miles (75 000 km)
D Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-56 for proper rotation pattern and additional
information. (See footnote
+.)
U Rotate tires. See Tire Inspection and Rotation on
50,000 Miles (83 000 km)
0 Change automatic transmission fluid and filter 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
you do not use your vehicle under any of these
conditions, change the fluid and filter at
100,000 miles
(166
000 km).
52,500 Milles (87 500 km)
U Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-56 for proper rotation pattern and additional
information. (See footnote
+.)
D Rotate tires. See Tire lnspection and Rotation on
60,000 Miles (100 000 km)
U Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-56 for proper rotation pattern and additional
information. (See footnote
+.)
Ll Replace fuel filter. An Emission Control Service.
(See footnote
t.)
lJ Inspect Evaporative Control 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.
An Emission Control Service. (See footnote
t.)
U Rotate tires. See Tire lnspection and Rotation on
6-i

100,000 Miles (166 000 km)
0 Inspect spark plug wires. An Emission Control
ii Repiace spark piugs. An Emission Zoniroi Service.
0 Change automatic transmission fluid and filter if
the vehicle is mainly driven under one or more
of these conditions:
Service.
- 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.
Ll If you haven’t used your vehicle under severe service
conditions listed previously and, therefore, haven’t
changed your automatic transmission fluid, change
both the fluid and filter.
150,000 Miles (240 000 km)
0 Drain, flush and refill cooling system (or every
60 months since last service, whichever occurs first). See
Engine Codant on page 5-22 for what to me.
Inspect hoses. Clean radiator, condenser, pressure
cap and neck. Pressure test the cooling system
and pressure cap. An Emission Control Service.
0 Inspect engine accessory drive belt. An Emission
Control Service.
U Inspect Positive Crankcase Ventilation (PCV) valve.
An Emission Control Service.
6-9

GM Mobility Program for Persons
with Disabilities
This program, avaiiabie io
qualified applicants, can
reimburse you up
to
$1,000 toward aftermarket
driver or passenger
adaptive equipment you
may require for your
vehicle (hand controls,
wheelchair/scooter lifts, etc.).
I I
This program can also provide you with free resource
information, such as area driver assessment centers and
mobility equipment installers. The program is available
for a limited period of time from the date of vehicle
purchase/lease. See your dealer for more details or call
the GM Mobility Assistance Center at 1-800-323-9935.
Text telephone (TTY) users, call 1-800-833-9935.
GM of Canada also has a Mobility Program. Call
1-800-GM-DRIVE (463-7483) for details.
All TTY users
call 1-800-263-3830.
Roadside Assistance Program
GMC’s Roadside Assistance Provides stranded owners
with over-the-phone roadside repairs, location of the
nearest
GhlC dealer or the following special services:
Flat Tire Change: Installation of spare tire will be
covered at no charge (customer is responsible for repair
or replacement of tire).
Fuel Delivery: Delivery of enough fuel for the customer
to get to the nearest service station (up to $5.00)
will be covered.
Jump Start: No-start situations which require a battery
jump start will be covered at no charge.
Lock Out: Replacement keys or locksmith service will be
covered at no charge
if you are unable to gain entry
into your vehicle. Delivery of the replacement key will be
covered within
10 miles (16 km).
Emergency Towing Service: Towing
to the nearest GMC
dealer for warranty related disablements will be
covered.
Trip Routing: Custom-made, computerized highlighted
maps using the most direct or scenic route are provided
free of charge. Maps include points of interest and a
list of GMC dealers along the route. Also included is a
list of hotels along the route that are discounted
7-5

Locks (cont.) Programmable Automatic Door Locks
............. 2-1 0
Rear Door Security Locks ............................. 2-1 2
Loss of Control ............................................... 4-15
LOW COOLANT LEVEL .................................. 3-53
Low Fuel Warning Light
................................... 3-42
Lumbar Luggage Carrier
.............................................. 2-42
Power Controls
..................................... 1-4
Maintenance. Normal Replacement Parts
............ 5-98
Maintenance Schedule At Each Fuel Fill
......................................... 6-10
At Least Once a Month
................................ 6-10
At Least Once a Year .................................. 6-1 1
At Least Twice a Year .................................. 6-10
Brake System Inspection
.............................. 6-14
Engine Cooling System Inspection
................. 6-14
Exhaust System Inspection
........................ 6-1 4
Fuel System Inspection
............. ............ 6-14
How This Section is Organized
....................... 6-3
Introduction
.................................................. 6-2
Maintenance Requirements
............................. 6-2
Part A
- Scheduled Maintenance Services ......... 6-4
Part B
- Owner Checks and Services ............. 6-10 Maintenance Schedule
(cont.)
Part C
. Periodic Maintenance Inspections ...... 6-14
Part D
. Recommended Fluids and Lubricants .... 6-15
Part E
. Maintenance Record ........................ 6-17
Scheduled MainteEance
................................. 6-5
Steering and Suspension Inspection ............... 6-14
Your Vehicle and the Environment
................... 6-2
Maintenance When Trailer Towing
..................... 4-55
Making Turns
................................................. 4-54
Malfunction Indicator Light
................................ 3-38
Matching Transmitter(s)
to Your Vehicle ............... 2-6
Message Mexico, Central America and Caribbean Islands/ Using
Your
................................................... 6-4
Memory Seat
................................................. 2-47
DIC Warnings and Messages
........................ 3-52
Countries (Except Puerto Rico and
US .
Virgin Islands) ............................................... 7-4
Mirrors Automatic Dimming Rearview with Onstar@,
Compass and Temperature Display
............. 2-31
Outside Automatic Dimming Mirror with Curb View Assist
............................................. 2-35
Outside Convex Mirror
................................. 2-34
Outside Heated Mirrors
................................ 2-35
Outside Power Mirrors
.................................. 2-34
MyGMLink.com
................................................ 7-3
9