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 transmission uid, change
both the uid and lter. 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 re ll cooling system (or every
60 months since last service, whichever occurs rst).
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.
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2003 - Sonoma OM
Also look for any opened or broken air bag coverings,
and have them repaired or replaced. (The air bag
system does not need regular maintenance.)
Wiper Blade Check
Inspect wiper blades for wear or cracking. Replace
blade inserts that appear worn or damaged or that
streak or miss areas of the windshield. Also see
Cleaning the Outside of Your Vehicle on page 5-82.
Spare Tire Check
At least twice a year, after the monthly in ation check of
the spare tire determines that the spare is in ated to
the correct tire in ation pressure, make sure that
the spare tire is stored securely. Push, pull, and then try
to rotate or turn the tire. If it moves, use the wheel
wrench to tighten the cable. SeeChanging a Flat Tire
on page 5-68.
Weatherstrip Lubrication
Silicone grease on weatherstrips will make them last
longer, seal better, and not stick or squeak. Apply
silicone grease with a clean cloth. During very cold,
damp weather more frequent application may be
required. SeePart D: Recommended Fluids and
Lubricants on page 6-33.
Manual Transmission Check
Check the transmission uid level; add if needed.
SeeManual Transmission Fluid on page 5-23. Check
for leaks. A uid leak is the only reason for uid
loss. Have the system inspected and repaired if needed.
Automatic Transmission Check
Check the transmission uid level; add if needed.
SeeAutomatic Transmission Fluid on page 5-20.A uid
loss may indicate a problem. Check the system and
repair if needed.
Hydraulic Clutch System Check
Check the uid level in the clutch reservoir. See
Hydraulic Clutch on page 5-24.
A uid loss in this system could indicate a problem.
Have the system inspected and repaired at once.
At Least Four Times a Year
Tailgate Lubrication Service
Lubricate tailgate latch bolt, handle assembly pivot
points, and hinges with lubricant recommended
in Part D.
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2003 - Sonoma OM