GMC Sierra Denali 2009 Owner's Manual page 470

(c) Visually inspect hoses and have them replaced if
they are cracked, swollen, or deteriorated. Inspect
all pipes, fittings, and clamps; replace with genuine
parts as needed. To help ensure proper operation, a
pressure test of the cooling system and pressure
cap and cleaning the outside of the radiator and air
conditioning condenser is recommended at least
once a year.
(d) Inspect wiper blades for wear, cracking, or
contamination. Clean the windshield and wiper blades, if
contaminated. Replace wiper blades that are worn or
damaged. See Windshield Wiper Blade Replacement on
page 5-61 and Windshield and Wiper Blades on
page 5-110 for more information.
(e) Make sure the safety belt reminder light and safety
belt assemblies are working properly. Look for any
other loose or damaged safety belt system parts. If you
see anything that might keep a safety belt system
from doing its job, have it repaired. Have any torn or
frayed safety belts replaced. Also see Checking
the Restraint Systems on page 1-72.
(f) Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
door hinges, liftgate hinge, liftgate linkage, liftgate handle
pivot points, latch bolt, fuel door hinge, locks, and
folding seat hardware. More frequent lubrication may be
required when exposed to a corrosive environment.
6-8
Applying silicone grease on weatherstrips with a clean
cloth will make them last longer, seal better, and
not stick or squeak.
(g) Inspect system. Check all fuel and vapor lines and
hoses for proper hook-up, routing, and condition. Check
that the purge valve works properly, if equipped.
Replace as needed.
(h) Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
− In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
− In hilly or mountainous terrain.
− When doing frequent trailer towing.
− Uses such as found in taxi, police, or delivery
service.
(i) Drain, flush, and refill cooling system. This service
can be complex; you should have your dealer/retailer
perform this service. See Engine Coolant on page 5-27
for what to use. Inspect hoses. Clean radiator,
condenser, pressure cap, and filler neck. Pressure test
the cooling system and pressure cap.
(j) A fluid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the fluid level checked. Add fluid if needed.