Without the GMC power steering lines and hoses being connected to the other steering components, the maneuvering of the vehicle would be extremely difficult. Like most systems on a vehicle, the power source of the power steering system is separate from the components that will utilize the pressure it generates. That makes the power steering hoses necessary so this transfer of pressure can be efficiently achieved. The GMC power steering lines and hoses are connected to the power steering pump on the front of the engine at one end. The other end is connected to the steering gear box generally located on the driver side of the front end. On all GMC trucks, the power steering lines will have an extreme level of pressurized hydraulic fluid in them when the system is in use. The only line that isn't under pressure is the return hose, which could lead back to the pump or to a reservoir. When a leak of the hydraulic fluid emanates from the power steering line or hose, a rush of fluid will appear. This will reduce the efficiency of your power steering system and make it extremely difficult for the driver to turn the steering wheel. If this condition is not addressed, air will be introduced to the power steering system cause the maneuvering of the GMC vehicle either extremely difficult or impossible. A leak in a power steering line or hose can be easily observed when there is pressure in the system. This occurs when the steering wheel is being turned while the engine is running. This will be a continuous loss of fluid until the hole is sealed with a replacement part. The lines and hoses cannot be repaired and must be replaced on your GMC truck so it can be safely operated on the road.