2003 GMC Sierra 1500 Pickup Owner's Manual - Page 420

How to Check Power Steering Fluid Turn the key off, let the engine compartment cool down, wipe the cap and the top of the reservoir clean, then unscrew the cap and wipethe dipstick with a clean rag. Replace the cap and completely tighten it. Then remove the cap again and look at the fluid level on the dipstick. The level should be at the FULL COLD mark. If necessary, add only enough fluid to bring the level up to the mark. What to Use All Other Engines To determine what kind of fluid to use, see Part D: Recommended Fluids and Lubricants on page 6-18. Always use the proper fluid. Failure to use the proper fluid can cause leaks and damage hoses and seals. When to Check Power Steering Fluid It is not necessary to regularly check power steering fluid unless you suspect there is a leak in the system or you hear an unusual noise. A fluid loss in this system could indicate a problem. Have the system inspected and repaired. See Engine Compartment Overview on page 5-12 for reservoir location. 5-45