2003 GMC SONOMA cooling

100,000 Miles (166 000 km)
❑Inspect spark plug wires.An Emission Control
Service.
❑Replace spark plugs.An Emission Control Service.
❑If you haven’t used your vehicle under severe service
conditions listed previously and, therefore, haven’t
changed your automatic transmissionuid, change
both theuid andlter. Manual transmission
uid doesn’t require change.
❑4.3L V6 Engine Only: Inspect Positive Crankcase
Ventilation (PCV) valve.An Emission Control
Service.
150,000 Miles (240 000 km)
❑Drain,ush and rell cooling system (or every
60 months since last service, whichever occursrst).
SeeEngine Coolant on page 5-25for what to use.
Inspect hoses. Clean radiator, condenser, pressure
cap and neck. Pressure test the cooling system
and pressure cap.An Emission Control Service.
❑Inspect engine accessory drive belt.An Emission
Control Service.
6-25
2003 - Sonoma OM

Part C: Periodic Maintenance
Inspections
Listed in this part are inspections and services which
should be performed at least twice a year (for instance,
each spring and fall).You should let your dealer’s
service department do these jobs. Make sure any
necessary repairs are completed at once.
Proper procedures to perform these services may be
found in a service manual. SeeService Publications
Ordering Information on page 7-9.
Steering, Suspension and Front
Drive Axle Boot and Seal Inspection
Inspect the front and rear suspension and steering
system for damaged, loose or missing parts, signs of
wear or lack of lubrication. Inspect the power steering
lines and hoses for proper hook-up, binding, leaks,
cracks, chang, etc. Clean and then inspect the drive
axle boot seals for damage, tears or leakage. Replace
seals if necessary.
Exhaust System Inspection
Inspect the complete exhaust system. Inspect the body
near the exhaust system. Look for broken, damaged,
missing or out-of-position parts as well as open seams,
holes, loose connections or other conditions which
could cause a heat build-up in theoor pan or could let
exhaust fumes into the vehicle. SeeEngine Exhaust
on page 2-37.
Fuel System Inspection
Inspect the complete fuel system for damage or leaks.
Engine Cooling System Inspection
Inspect the hoses and have them replaced if they
are cracked, swollen or deteriorated. Inspect all pipes,
ttings and clamps; replace as needed. Clean the
outside of the radiator and air conditioning condenser.
To help ensure proper operation, a pressure test of
the cooling system and pressure cap is recommended
at least once a year.
6-31
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

Headlamps (cont.)
Halogen Bulbs............................................5-50
One-Piece Front Turn Signal Lamps...............5-52
Two-Piece Front Turn Signal Lamps...............5-53
Heated Seats................................................... 1-5
Heating.........................................................3-18
Highway Hypnosis...........................................4-34
Hill and Mountain Roads..................................4-34
Hitches..........................................................4-56
Hood
Checking Things Under.................................. 5-8
Release....................................................... 5-9
Horn ............................................................... 3-4
How to Add Coolant to the Coolant
Recovery Tank............................................5-32
How to Add Coolant to the Radiator..................5-34
How to Add Fluid....................................5-22, 5-24
How to Check................................5-20, 5-23, 5-59
How to Check and Add Fluid
............................5-25
How to Check Lubricant
..........................5-47, 5-49
How to Check Power Steering Fluid
..................5-37
How to Inspect the Engine Air Cleaner/Filter
.......5-19
How to Use This Manual
...................................... ii
How to Wear Safety Belts Properly
...................1-15
Hydraulic Clutch
.............................................5-24
Hydraulic Clutch System Check
........................6-27
Hydroplaning
..................................................4-30I
If No Steam Is Coming From Your Engine..........5-29
If Steam Is Coming From Your Engine...............5-28
If the Light Is Flashing.....................................3-30
If the Light Is On Steady.................................3-31
If You Are Stuck in Sand, Mud, Ice or Snow.......4-40
If You Do Decide To Pull A Trailer.....................4-52
If You’re Caught in a Blizzard...........................4-38
Ignition Positions.............................................2-20
Ignition Transmission Lock Check......................6-29
Infants and Young Children, Restraints...............1-32
Inflation–Tire Pressure...................................5-58
Inspection
Brake System.............................................6-32
Engine Cooling System................................6-31
Exhaust System..........................................6-31
Fuel System...............................................6-31
Part C - Periodic Maintenance.......................6-31
Steering, Suspension and Front Drive
Axle Boot and Seal..................................6-31
Throttle System...........................................6-32
Transfer Case and Front Axle
(Four-Wheel Drive)...................................6-32
Installing a Garage Door Opener.......................2-43
Instrument Panel
Cluster.......................................................3-21
Overview..................................................... 3-2
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2003 - Sonoma OM

Locks
Door ........................................................... 2-8
Leaving Your Vehicle....................................2-11
Lockout Protection.......................................2-11
Power Door .................................................. 2-9
Programmable Automatic Door Locks............... 2-9
Rear Door Security Locks.............................2-11
Long Trip/Highway Definition.............................. 6-6
Long Trip/Highway Intervals............................... 6-6
Long Trip/Highway Scheduled Maintenance........6-18
Loss of Control...............................................4-12
Low Fuel Warning Light...................................3-35
Luggage Carrier..............................................2-50
Lumbar
Manual Controls............................................ 1-4
Power Controls............................................. 1-5
M
Maintenance, Normal Replacement Parts............5-96
Maintenance Schedule
At Each Fuel Fill.........................................6-26
At Least Four Times a Year..........................6-27
At Least Once a Month................................6-26
At Least Once a Year..................................6-28
At Least Twice a Year..................................6-26Maintenance Schedule (cont.)
Brake System Inspection..............................6-32
Engine Cooling System Inspection.................6-31
Exhaust System Inspection...........................6-31
Fuel System Inspection................................6-31
How This Section is Organized....................... 6-3
Introduction.................................................. 6-2
Long Trip/Highway Scheduled Maintenance.....6-18
Maintenance Requirements............................. 6-2
Part A - Scheduled Maintenance Services......... 6-4
Part B - Owner Checks and Services.............6-26
Part C - Periodic Maintenance Inspections......6-31
PartD-Recommended Fluids and
Lubricants...............................................6-33
PartE-Maintenance Record........................6-35
Selecting the Right Schedule
.......................... 6-5
Short Trip/City Scheduled Maintenance
............. 6-7
Steering, Suspension and Front Drive
Axle Boot and Seal Inspection
...................6-31
Throttle System Inspection
............................6-32
Transfer Case and Front Axle
(Four-Wheel Drive) Inspection
....................6-32
Using Your
................................................... 6-4
Your Vehicle and the Environment
................... 6-2
Maintenance When Trailer Towing
.....................4-60
Making Turns
.................................................4-58
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2003 - Sonoma OM