2003 GMC YUKON DENALI coolant temperature

Engine Coolant Heater
Your vehicle may be equipped with an engine
coolant heater.
I
Usually, the coolant heater sho In very cold weather,
0°F
(-18°C) or
colder, the
engine coolant heater can
help. You’ll get easier
starting and better
fuel economy during
engine warm-up.
luld be ph Jgged in a
minimum of four hours prior to starting your vehicle.
At temperatures above 32°F (OOC), use of the coolant
heater is not required.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord.
The cord is located on the driver’s side of the
engine compartment, near the power steering
fluid reservoir. 3.
Plug it into a normal, grounded 1 IO-volt AC outlet.
PIL,ging the cord inl, an ,..grc,.lded out.,_
could cause an electrical shock. Also, the
wrong kind
of extension cord could overheat
and cause a fire. You could be seriously
injured. Plug the cord into a properly grounded
three-prong
11 0-volt AC outlet. If the cord
won’t reach, use a heavy-duty three-prong
extension cord rated for at least
15 amps.
4. Before starting the engine, be sure to unplug and
store the cord as it was before to keep it away
from moving engine parts.
If you don’t, it could be
damaged.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead
of trying to list everything here, we ask that you contact
your dealer in the area where you’ll be parking your
vehicle. The dealer can give you the best advice for that
particular area.
2-21

Section 3 Instrument Panel
Instrument Panel Overview ............................... 3.4
Hazard Warning Flashers
................................ 3.5
Other Warning Devices ................................... 3.6
Horn
............................................................. 3.6
Tilt Wheel
..................................................... 3-6
Turn SignaVMultifunction Lever
......................... 3.7
Exterior Lamps
............................................. 3.13
Interior Lamps
.............................................. 3.16
Accessory Power Outlets
............................... 3.17
Ashtrays and Cigarette Lighter
........................ 3.18
Climate Controls ............................................ 3. 1 9
Electronic Climate Control System
................... 3.19
Outlet Adjustment
......................................... 3.25
Rear Climate Control System
......................... 3.25
Climate Controls Personalization
..................... 3.27
Warning Lights, Gages and Indicators ............. 3.28
Instrument Panel Cluster
................................ 3.29
Speedometer and Odometer
........................... 3.30
Tachometer
................................ ......... 3.30
~
Safety Belt Reminder Light ............................. 3.30
Air Bag Readiness Light
................................ 3.31
Passenger Air Bag Status Indicator ................ -3-32
Charging System Light
.................................. 3-33
Voltmeter Gage
............................................ 3-34
Brake System Warning Light
...................... 3-34
Anti-Lock Brake System Warning Light
........................................... 3-35
Traction
Off Light .......................................... 3-36
Transmission Temperature Gage
..................... 3-37
Malfunction Indicator Lamp
............................. 3-38
Oil Pressure Gage ........................................ 3-40
Security Light
............................................... 3-41
Tow/Haul Mode Light .................................... 3-42
Fuel Gage
................................................... 3-42
Low Fuel Warning Light
............................. 3-42
Engine Coolant Temperature Gage
.................. 3-36
Cruise Control
Light ...................................... 3-41
3- 1

2. Set the driver’s and passenger’s temperature.
To find your comfort setting, start with a
74°F (23°C)
temperature setting and allow about
20 minutes
for the system to regulate. Turn the driver’s or
passenger’s side temperature knob
to adjust the
temperature setting as necessary.
If you choose the temperature setting of 60°F
(15°C) the system will remain at the maximum
cooling setting.
If you choose the temperature
setting of
90°F (32°C) the system will remain at the
maximum heat setting. Choosing either maximum
setting will not cause the vehicle to heat or cool
any faster.
Be careful not to cover the sensor located on the
top of the instrument panel near the windshield. This
sensor regulates air temperature based on sun
load, and also turns on your headlamps.
To avoid blowing cold air in cold weather, the
system will delay turning on the fan until warm air is
available. The length of delay depends on the
engine coolant temperature. Pressing the fan switch
will override this delay and change the fan to a
selected speed.
Manual Operation
You may manually adjust the air delivery mode or
fan speed.
0 (Off): Press this button to turn off the entire climate
control system. Outside air will still enter the vehicle, and
will be directed
to the floor. This direction can be changed
by pressing the mode button. The temperature can also
be adjusted using either temperature knob. Press the up
or down arrows on the fan switch, the defrost button, the
AUTO button, or the air conditioning button to turn the
system on when it is
off.
v (Fan): The switch with the fan symbol allows
you
to manually adjust the fan speed. Press the up
arrow
to increase fan speed and the down arrow
to decrease fan speed.
Pressing this button when the system
is off will turn the
system on.
% *d (Mode): Press this button to manually change the
direction of the airflow in your vehicle; keep pressing the
button until the desired mode appears on the display.
If you press the mode button to select an air delivery
mode, the display will change to show you the selected
air mode delivery. The display will then show the
current status of the system. When the system is turned
off, the display will go blank after displaying the
current status of the system.
3-21

If the light stays on, or comes on when you’re driving,
your vehicle needs service. You will also hear a
chime sound when the light is on steady.
If the regular
brake system warning light isn’t on, you still have
brakes, but you don’t have anti-lock brakes.
If the
regular brake system warning light is also on you don’t
have anti-lock brakes and there’s a problem with
your regular brakes. In addition to both lights, you will
also hear a chime sound on the first occurrence of
a problem and each time the car is shut off and then
restarted. See Brake System Warning Light on
page
3-34.
Traction Off Light
If you have the
Stabilitrak@system, this
light should come on briefly
when you turn the
ignition to
RUN.
If the light doesn’t come on then, the system may
require service; have it fixed
so it will be there to warn
you
if the system is turned off.
For more information on the traction off light, see
Stabilitrak@
System on page 4-9.
3-36
Engine Coolant Temperature Gage
~~ ~
United States
I I
Canada
This gage shows the engine coolant temperature.
It also provides an indicator
of how hard your vehicle is
working. During a majority of the operation, the gage
will read 21
0°F (100°C) or less. If you are pulling a load
or going up hills, it is normal for the temperature to
fluctuate and approach the 250°F (122°C) mark.
If the
gage reaches the 260°F
(125°C) mark, it indicates
that the cooling system
is working beyond its capacity.
See Engine Overheating on page
5-25.

OIL LIFE RESET ENGINE COOLANT HOT
This message will appear on the display for about
10 seconds after resetting the change engine oil
message.
OIL PRESSURE LOW
If low oil pressure levels occur, this message will be
displayed on the DIC and a chime will sound. Stop the
vehicle as soon as safely possible and do not operate
it until the cause of the low oil pressure has been
corrected. Check your oil as soon as possible and have
your vehicle serviced.
CHECK OIL LEVEL
If the oil level in the vehicle is low, this message will
appear on the DIC. Check the oil level and correct it as
necessary. You may need
to let the vehicle cool or
warm up and cycle the ignition
to be sure this message
will clear. Once the problem is corrected, pressing
the select button will clear this message from the DIC
display. This message will clear itself after
10 seconds
until the next igntion cycle.
LOW COOLANT LEVEL
If the engine coolant level is low, this message will
appear on the DIC. Adding coolant will clear the
message. This message will clear itself after
10 seconds
until the next igntion cycle. If
the cooling system temperature gets hot, this message
will appear in the DIC. Stop the vehicle and
let the
engine idle in PARK
(P) to allow the coolant to reach a
safe temperature. This message will clear when the
coolant temperature drops
to a safe operating
temperature.
ENGINE OVERHEATED
If the engine cooling system reaches unsafe
temperatures for operation, this message will appear in
the DIC and you will hear a chime. Stop and turn
off
the vehicle as soon as it is safe to do so to avoid severe
damage. This message will clear when the engine
has cooled
to a safe operating temperature.
REDUCED ENGINE POWER
This message is displayed and you will hear a chime
when the cooling system temperature gets too hot
and the engine further enters the engine coolant
protection mode.
See
Engine Overheating on page 5-25 for further
information.
3-53

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.
Turn Signals When Towing a Trailer
The arrows on your instrument panel will flash whenever
you signal a turn or lane change. Properly hooked up,
the trailer lamps will also flash, telling other drivers
you’re about
to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument panel will flash for turns even
if the bulbs on the trailer
are burned out. Thus, you may think drivers behind
4-54
you are seeing your signal when they are not. It’s
important to check occasionally to be sure the trailer
bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gear before you start
down a long or steep downgrade.
If you don’t shift
down, you might have to use your brakes
so much that
they would get hot and no longer work well.
You can tow in
DRIVE (D). You may want to shift the
transmission
to THIRD (3) or, if necessary, a lower gear
selection
if the transmission shifts too often
(e.g., under heavy loads and/or hilly conditions).
You may also want
to activate the tow/haul mode if the
transmission shifts
too often. See “Tow/Haul Mode”
under Towing a Trailer
on page 4-47.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes.
If you turn your
engine
off immediately after towing at high altitude
on steep uphill grades, your vehicle may show signs
similar
to engine overheating. To avoid this, let the
engine run while parked (preferably on level ground)
with the automatic transmission in PARK (P) for a
few minutes before turning the engine
off. If you do get
the overheat warning, see Engine Overheating
on
page 5-25.

The following explains your cooling system and how to
add coolant when it is low. If you have a problem
with engine overheating, see Engine Overheating
on
page 5-25.
A 50/50 mixture of clean, drinkable water and
DEX-COOL@ coolant will:
Give freezing protection down to -34°F (-37°C).
Give boiling protection up to 265°F (129°C).
Protect against rust and corrosion.
Help keep the proper engine temperature.
e Let the warning lights and gages work as they
should.
Notice: When adding coolant, it is important that
you use only
DEX-COOL@ (silicate-free) coolant.
If coolant other than DEX-COOL@ is added to the
system, premature engine, heater core or radiator
corrosion may result. In addition, the engine coolant
will require change sooner
-- at 30,000 miles
(50,000 km) or 24 months, whichever occurs first.
Damage caused by the use of coolant other than
DEX-COQL.@ is not covered by your new vehicle
warranty.
What to Use
Use a mixture of one-half clean, drinkable water and
one-half DEX-COOL@ coolant which won’t damage
aluminum parts.
!f YOU uss this coolant mixture,
you don’t need
to add anything else.
Adding c..ly
c water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can boil before the proper coolant mixture will. Your
vehicle’s coolant warning system
is set for the
proper coolant mixture. With plain water or the
wrong mixture, your engine could get too hot
but you wouldn’t get the overheat warning.
Your engine could catch fire and you or others
could be burned. Use a
50/50 mixture of clean,
drinkable water and DEX-COQL@ coolant.
Notice: If you use an improper coolant mixture,
your engine could overheat and be badly damaged.
The repair cost wouldn’t be covered by your
warranty. Too much water
in the mixture can freeze
and crack the engine, radiator, heater core and
other parts.
5-23

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