2003 GMC SONOMA heater

Cooling System
When you decide it’s safe to lift the hood, here’s what
you’ll see:
A. Coolant Recovery Tank
B. Radiator Pressure Cap
C. Engine Cooling Fan
If the coolant inside the coolant recovery tank is boiling,
don’t do anything else until it cools down. The vehicle
should be parked on a level surface.When the engine is cold, the coolant level should be at
least up to the ADD mark. If it isn’t, 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.
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2003 - Sonoma OM

{CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Don’t touch them. If you
do, you can be burned.
Don’t run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an enginere, and you could be
burned. Get any leakxed before you drive the
vehicle.
If there seems to be no leak, start the engine again.
The engine cooling fan speed should increase when idle
speed is doubled by pushing the accelerator pedal
down. If it doesn’t, your vehicle needs service. Turn off
the engine.Notice:Engine damage from running your engine
without coolant isn’t covered by your warranty.
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 occursrst.
Damage caused by the use of coolant other
than DEX-COOL
®is not covered by your new
vehicle warranty.
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2003 - Sonoma OM

How to Add Coolant to the Coolant
Recovery Tank
If you haven’t found a problem yet, but the coolant level
isn’t at the ADD mark, add a 50/50 mixture ofclean,
drinkable waterand DEX-COOL
®engine coolant at the
coolant recovery tank. SeeEngine Coolant on
page 5-25for more information.
{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 wouldn’t get the overheat warning.
Your engine could catchre 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.
{CAUTION:
You can be burned if you spill 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.
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2003 - Sonoma OM

Coolant
Engine Temperature Gage............................3-29
Heater, Engine............................................2-24
Cooling.........................................................3-18
Cooling System..............................................5-30
Crew Cab
®....................................................1-46
Cruise Control.................................................. 3-8
Current and Past Model Order Forms................7-10
Customer Assistance Information
Courtesy Transportation.................................. 7-7
Customer Assistance for Text Telephone (TTY)
Users....................................................... 7-3
Customer Assistance Offices........................... 7-4
Customer Satisfaction Procedure..................... 7-2
GM Mobility Program for Persons with
Disabilities................................................ 7-5
Reporting Safety Defects to General Motors...... 7-9
Reporting Safety Defects to the Canadian
Government.............................................. 7-9
Reporting Safety Defects to the United States
Government.............................................. 7-8
Roadside Assistance Program......................... 7-5
Service Publications Ordering Information......... 7-9
D
Daytime Running Lamps..................................3-12
Defensive Driving............................................. 4-2
Defogging and Defrosting.................................3-19Dinghy Towing................................................4-43
Directing the Airflow ........................................3-17
Doing Your Own Service Work........................... 5-3
Dolly Towing..................................................4-44
Dome Lamp ...................................................3-15
Door
Locks.......................................................... 2-8
Power Door Locks......................................... 2-9
Programmable Automatic Door Locks............... 2-9
Rear Door Security Locks.............................2-11
Third Door..................................................2-12
Driver
Position, Safety Belt.....................................1-16
Driver Information Center (DIC).........................2-46
Driving
At Night.....................................................4-27
City ...........................................................4-31
Defensive..................................................... 4-2
Drunken....................................................... 4-2
Freeway.....................................................4-32
Hill and Mountain Roads..............................4-34
In Rain and on Wet Roads...........................4-28
Winter........................................................4-36
Driving Across an Incline..................................4-22
Driving Downhill..............................................4-21
Driving in Mud, Sand, Snow or Ice....................4-25
Driving in Water..............................................4-26
Driving On Grades
..........................................4-59
Driving on Off-Road Hills
.................................4-18
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2003 - Sonoma OM

Driving on Snow or Ice....................................4-37
Driving Through Deep Standing Water...............4-30
Driving Through Flowing Water.........................4-30
Driving Uphill..................................................4-19
Driving with a Trailer.......................................4-57
E
Electrical System
Add-On Equipment......................................5-88
Fuses and Circuit Breakers...........................5-89
Headlamps.................................................5-88
Power Windows and Other Power Options......5-88
Windshield Wiper Fuses...............................5-88
Electronic Transfer Case..................................2-30
Emissions Inspection and Maintenance
Programs...................................................3-32
Engine
Air Cleaner/Filter.........................................5-18
Battery.......................................................5-42
Check and Service Engine Soon Light............3-29
Compartment Overview................................5-10
Coolant......................................................5-25
Coolant Heater............................................2-24
Coolant Temperature Gage...........................3-29
Cooling System Inspection............................6-31
Exhaust.....................................................2-37
Fan Noise..................................................5-36Engine (cont.)
Oil .............................................................5-13
Overheating................................................5-28
Starting......................................................2-22
Engine Compartment Fuse Block......................5-91
Engine Coolant Level Check.............................6-26
Engine Oil Additives........................................5-16
Engine Oil Level Check...................................6-26
Entry Lighting.................................................3-14
Environmental Concerns..................................4-15
Exit Lighting...................................................3-14
Express Down Window....................................2-15
Extended Cab (Jump Seat)..............................1-48
Extender, Safety Belt.......................................1-29
Exterior Lamps...............................................3-10
F
Fabric/Carpet.................................................5-79
Filter
Engine Air Cleaner......................................5-18
Finding a PTY Station.....................3-43, 3-50, 3-60
Finding a Station....................3-38, 3-40, 3-48, 3-57
Finish Care....................................................5-83
Finish Damage...............................................5-85
Five-Speed....................................................2-28
Fixed Mast Antenna........................................3-69
Flash-To-Pass Feature....................................... 3-6
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2003 - Sonoma OM

Stalling on an Incline.......................................4-24
Starter Switch Check.......................................6-28
Starting Your Engine.......................................2-22
Shifting Into................................................2-22
Starting Your VORTEC™2200 L4 Engine............ 6-4
Starting Your VORTEC™4300 V6 Engine..........2-23
Steering.......................................................... 4-8
Steering in Emergencies.................................... 4-9
Steering, Suspension and Front Drive
Axle Boot and Seal Inspection.......................6-31
Steering Tips................................................... 4-8
Storage
Garment Hooks...........................................2-50
Storage Areas
Front Storage Area......................................2-49
Glove Box..................................................2-41
Luggage Carrier..........................................2-50
Overhead Console.......................................2-42
Storing a Flat or Spare Tire and Tools...............5-76
Stuck in Sand, Mud, Ice or Snow......................4-40
Sun Visors.....................................................2-16
Sunglasses Storage Compartment.....................2-46
Sunroof.........................................................2-52
Swing-Out Windows........................................2-16
T
Tachometer....................................................3-23
Tailgate.........................................................2-12Tailgate Lubrication Service..............................6-27
Taillamps.......................................................5-55
Temperature and Compass Display....................2-44
Testing the Alarm............................................2-18
Theft-Deterrent, Radio.....................................3-67
Theft-Deterrent Systems...................................2-17
Content Theft-Deterrent
................................2-17
Passlock
®...................................................2-19
Third Door
.....................................................2-12
Throttle System Inspection
...............................6-32
Tilt Wheel
........................................................ 3-4
Time Delay
....................................................2-39
Tire Inflation Check
.........................................6-26
Tires
.....................................................5-58, 5-84
Buying New Tires
........................................5-62
Chains
.......................................................5-66
Changing a Flat Tire
....................................5-68
Compact Spare Tire
.....................................5-78
If a Tire Goes Flat
.......................................5-67
Inflation–Tire Pressure
...............................5-58
Inspection and Rotation
................................5-60
Uniform Tire Quality Grading
.........................5-63
Wheel Alignment and Tire Balance
.................5-64
Wheel Replacement
.....................................5-65
When It Is Time for New Tires
......................5-61
To Use the Engine Coolant Heater
....................2-24
Top of the Instrument Panel
.............................5-81
Top Strap
......................................................1-41
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2003 - Sonoma OM