Symptom Related Diagnostic Procedures

Troubles with the power steering system are usually concerned with hard steering due to the fact that there is no assistance. In such a case, before attempting to make repairs, it is necessary to determine whether the trouble lies with the pump or with the gear housing. To do this, an on vehicle inspection can be made by using a pressure gauge as outlined under ON-VEHICLE INSPECTIONS.
The power steering system is a hydraulic device and problems are normally due to insufficient fluid pressure acting on the piston. This could be caused by either the power steering pump or the gear housing.
If the fault lies in the pump, the same symptoms will generally occur whether the steering wheel is turned fully to the right or left. If the fault lies in the control valve, there will generally be a difference between the amount of assist when the steering wheel is turned in either direction. If the piston seal of the rack and pinion is worn, there will be a loss of fluid pressure whenever the steering wheel is turned and symptoms will be the same in both directions.
Before performing an on-vehicle inspection, a check must be made to confirm that there is no air in the system. If any air is in the system, the volume of this air will change when the fluid pressure is raised, causing a fluctuation in the fluid pressure so that the power steering will not function correctly. Also, air in the system will sometimes result in an abnormal noise occurring from the pump or gear housing when the steering wheel is turned in either direction.
To determine if there is any air in the system, check to see if there is a change of fluid level in the reservoir tank when the steering wheel is turned fully to the right or left.
On these models, inspections must be performed every time to ensure the power steering system is operating correctly after overhauling or repairing the pump or gear housing.