2005 GMC YUKON engine overheat

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 5-15.
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. Engine Cooling Fan8100 V8 Engines
5-29

A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Cooling Fan
{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.
If the coolant inside the coolant surge tank is boiling, do
not do anything else until it cools down. The vehicle
should be parked on a level surface. Check the coolant
level after the system cools down. Some amount of
coolant may be lost due to overheating.
The coolant level should
be at or above the FULL
COLD mark. If it is not, you
may have a leak at the
pressure cap or in
the radiator hoses, heater
hoses, radiator, water
pump or somewhere else
in the cooling system. All Other Engines
5-30

{CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Do not touch them.
If you do, you can be burned.
Do not run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an engine re, and you could be
burned. Get any leak xed before you drive the
vehicle.
If your vehicle is equipped with an electric engine
cooling fan, check the coolant temperature gage. If the
coolant temperature is approximately 232°F (111°C),
the electric cooling fan should be running. If it is
not, your vehicle needs service. Turn off the engine.
If your vehicle is equipped with an engine-driven cooling
fan, start the engine again and see if the fan speed
increases when idle speed is doubled by pushing the
accelerator pedal down. If it does not, your vehicle
needs service. Turn off the engine.Notice:Engine damage from running your engine
without coolant is not covered by your warranty. See
Overheated Engine Protection Operating Mode on
page 5-29for information on driving to a safe place
in an emergency.
Notice:Using coolant other than DEX-COOL®may
cause premature engine, heater core or radiator
corrosion. In addition, the engine coolant may
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your vehicle.
How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level is not at or above the FULL COLD
mark, add a 50/50 mixture ofclean, drinkable water
and DEX-COOL
®coolant at the coolant surge tank,
but be sure the cooling system, including the coolant
surge tank pressure cap, is cool before you do it.
SeeEngine Coolant on page 5-24for more information.
5-31

If no coolant is visible in the surge tank, add coolant as
follows:
{CAUTION:
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They
are under pressure, and if you turn the coolant
surge tank pressure cap — even a little — they
can come out at high speed. Never turn the
cap when the cooling system, including the
coolant surge tank pressure cap, is hot. Wait
for the cooling system and coolant surge tank
pressure cap to cool if you ever have to turn
the pressure cap.
{CAUTION:
Adding only plain 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 would not get the overheat warning.
Your engine could catch re and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.
Notice:In cold weather, water can freeze and crack
the engine, radiator, heater core and other parts.
Use the recommended coolant and the proper
coolant mixture.
5-32

Door
Delayed Locking..........................................2-10
Locks.......................................................... 2-8
Power Door Locks......................................... 2-9
Programmable Automatic Door Locks.............2-10
Rear Door Security Locks.............................2-12
Driver
Position, Safety Belt.....................................1-28
Driver Information Center (DIC).........................3-54
DIC Operation and Displays..........................3-55
DIC Vehicle Customization............................3-68
DIC Warnings and Messages........................3-58
Driving
At Night.....................................................4-36
City...........................................................4-40
Defensive..................................................... 4-2
Drunken....................................................... 4-2
Freeway.....................................................4-41
Hill and Mountain Roads..............................4-43
In Rain and on Wet Roads...........................4-37
Off-Road....................................................4-21
Recovery Hooks..........................................4-50
Rocking Your Vehicle to Get it Out.................4-50
Winter........................................................4-45
Dual Automatic Climate Control System.............3-24
Dual Climate Control System............................3-22
DVD
Rear Seat Entertainment System..................3-118E
Electrical System
Add-On Equipment.....................................5-105
Center Instrument Panel Fuse Block.............5-108
Fuses and Circuit Breakers.........................5-105
Instrument Panel Fuse Block.......................5-106
Power Windows and Other Power Options....5-105
Underhood Fuse Block...............................5-109
Windshield Wiper Fuses.............................5-105
Engine
Air Cleaner/Filter.........................................5-19
Battery.......................................................5-40
Check and Service Engine Soon Light............3-48
Coolant......................................................5-24
Coolant Heater............................................2-22
Coolant Temperature Gage...........................3-46
Engine Compartment Overview......................5-12
Exhaust.....................................................2-39
Fan Noise..................................................5-34
Oil .............................................................5-15
Oil Life System...........................................5-18
Overheated Protection Operating Mode...........5-29
Overheating................................................5-27
Starting......................................................2-21
Entry Lighting.................................................3-18
Event Data Recorders (EDR)............................. 7-8
Exit Lighting...................................................3-18
Extender, Safety Belt.......................................1-42
5

N
Navigation/Radio System, see
Navigation Manual.....................................3-118
New Vehicle Break-In......................................2-19
Normal Maintenance Replacement Parts............6-15
O
Odometer......................................................3-38
Odometer, Trip...............................................3-38
Off-Road Driving.............................................4-21
Off-Road Recovery..........................................4-18
Oil
Engine.......................................................5-15
Pressure Gage............................................3-51
Oil, Engine Oil Life System..............................5-18
Older Children, Restraints................................1-43
Online Owner Center........................................ 7-3
OnStar
®System, see OnStar®Manual...............2-50
Other Warning Devices...................................... 3-6
Outlet Adjustment............................................3-30
Outside
Automatic Dimming Mirror.............................2-49
Camper-Type Mirrors....................................2-47
Convex Mirror.............................................2-49
Curb View Assist Mirrors..............................2-49Outside (cont.)
Heated Mirrors............................................2-49
Manual Mirrors............................................2-46
Power Foldaway Mirrors...............................2-48
Power Mirrors.............................................2-47
Outside Power Camper-Type Mirror...................2-47
Overheated Engine Protection Operating Mode.....5-29
Owner Checks and Services.............................. 6-9
Owners, Canadian............................................... ii
P
Park (P)
Shifting Into................................................2-36
Shifting Out of............................................2-38
Parking
Brake........................................................2-35
Over Things That Burn.................................2-39
Passenger Airbag Status Indicator.....................3-40
Passenger Sensing System..............................1-75
Passing.........................................................4-18
Passlock
®......................................................2-19
Power
Accessory Outlets........................................3-20
Door Locks.................................................. 2-9
Electrical System.......................................5-105
10