1998 GMC Jimmy Owner's Manual - Page 296

Thermostat Engine coolant temperature is controlled a thermostat by in the engine coolant system. The thermostat stops the flow of coolant throughthe radiator until the coolant reaches a preset temperature. When to Check Power SteeringFluid 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. Power Steering Fluid How To Check Power Steering Fluic When the engine compartment is cool, wipe the cap and the top of the reservoir clean, then unscrew the cap and wipe the 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 between the ADD and FULL marks. If necessary, add only enough fluid to bring the level up to the proper range. What to CJse To determine what kind of fluid to use, see "Recommended Fluids and Lubricants'' in the Index. Always use the proper fluid. Failure use the proper to fluid can cause leaks anddamage hoses and seals. 6-27