Steering: Description and Operation

Steering System
The power steering system consists of:
^ power steering pump
^ fluid reservoir
^ rack and pinion steering gear
^ fluid cooler
^ power steering pressure and return lines/hoses

Principles of Operation
Power Steering
The power steering system uses a CIII power steering vane-type pump to pump the fluid from the reservoir to the rack-and-pinion steering gear. The power steering pump is mounted to the engine and driven by a drive belt from the crankshaft of the engine. Power steering fluid is pulled into one side of the pump from the reservoir by vacuum. The minimum vacuum required is 68 - 84 kpa (20 - 25 in-Hg). The power steering fluid is then trapped and squeezed into a smaller area inside the pump. This action pressurizes the fluid at the output, as it flows to the rest of the system. A pressure relief/flow valve is built into the pump to control the maximum pressure. The relief pressure is between (1,450 - 1,580 psi). This action prevents damage to the system during different engine speeds. The power steering fluid while under pressure flows through the high pressure power steering line to the rack and pinion steering gear.

Steering Column
The steering column is the mechanical linkage between the steering wheel and the steering gear. It houses many different switches and is able to tilt to various positions for driver preference. It starts with the steering wheel bolted to a shaft that runs down the center of the column to the upper steering shaft. The upper steering shaft goes through the dash panel and connects to the lower steering shaft and the lower shaft is then connected to the steering gear. The upper and lower shaft connections are made by U-joint type knuckles. The steering shaft is centered by various roller ball bearings which are housed by the casing of the steering column. The tilt steering wheel is controlled by a mechanical lever on the side of the steering column which uses a cam to lock and unlock the steering wheel. When the tilt wheel is unlocked it allows the steering wheel to adjust to various positions, using a pin-type pivot in the steering column. On vehicles equipped with the gear selector mounted on the steering column, the steering column uses a cable to select the transmission gear. The steering column switches (multifunction and ignition) are mounted to the steering column. These switches are covered by the upper and lower steering wheel shrouds and can be accessed by removing them.

Steering Column Switches
The steering column switches include the ignition switch (electrical) and the multifunction switch (headlamp dimmer/flash to pass, turn signal, and windshield wiper). The ignition switch is controlled by the lock cylinder key. When the lock cylinder key is turned to a selected position, a mechanical linkage allows the ignition switch to send voltage to specific components. The multifunction switch controls the various components electrically. The headlamp dimmer/flash to pass switch (part of the multifunction switch) sends voltage to the headlamps. The flash to pass switch is a momentary switch used to send voltage only to the high beam headlamps. The headlamp dimmer is used to switch voltages between the low and high beam headlamps while the headlamps are on. The turn signal switch lever (part of the multifunction switch) operates the left and right turn signals. When the desired turn signal is pressed, voltage passes through the smart junction box (SJB) to the selected turn signal, causing the turn signals to flash. The windshield wiper switch (part of the multifunction switch) uses a ground signal to activate the various wiper modes.