2008 GMC Yukon Owner's Manual - Page 502

(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 5-62 and Windshield, Backglass, and Wiper Blades on page 5-113 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 1-92. (f) Lubricate all key lock cylinders, hood latch assembly, secondary latch, pivots, spring anchor, release pawl, rear compartment hinges, outer liftgate handle pivot points, rear door detent link, roller mechanism, liftgate handle pivot points, latch bolt, fuel door hinge, cargo 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) Check vent hose at transfer case for kinks and proper installation. (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 5-28 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. (k) 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.