Power Steering Pump: Description and Operation

NORMAL OPERATION
The CIII power steering pump has the following features:
^ It is a belt driven, vane-type power steering pump.
^ It is mounted directly to the engine block by four retaining bolts.
^ An electronic variable orifice (EVO) power steering control valve actuator is connected to the pump body to control speed sensitive power steering assist.
^ The electrical connector and casing are able to swivel. This is normal and does not indicate a loose power steering control valve actuator assembly.
^ The power steering oil reservoir for the power steering fluid is mounted on the LH apron.
^ An identification tag attached to the power steering pump indicates the model number and bar code. Refer to these when a new power steering pump is required.
^ The power steering pump is serviced as an assembly. If any service is required, the entire power steering pump assembly must be replaced.
^ The only exception is if the power steering control valve actuator or connector on the power steering pump assembly is found to be damaged; then replace the power steering control valve actuator only.
^ A filter is built into the power steering pump reservoir. Check for contamination and clean or replace the reservoir assembly as required.

FAIL SAFE
In the event of an electrical circuit malfunction, such as circuit open, shorted, or electronic variable orifice (EVO) control module failure, the power steering control valve actuator will provide full power steering assist during such failure modes. Continued operation under such conditions may cause excessively high power steering fluid temperature and damage the steering components.

PRESSURE RELIEF VALVE OPERATION
Located in the power steering pump valve body, the pressure relief valve limits hydraulic pressure within the power steering gear to a preset maximum.