Steering, Suspension & Tires
Power steering types, wheel alignment angles (toe, camber, caster), and TPMS operation.
- Compare hydraulic and electric power steering systems
- Define and explain toe, camber, and caster alignment angles
- Describe TPMS operation and warning thresholds
- Diagnose common steering and alignment complaints
Lesson 1
Power Steering - Hydraulic & Electric (EPS)
Hydraulic Power Steering
Traditional hydraulic power steering uses a belt-driven power steering pump to pressurize fluid. This pressurized fluid assists the driver's steering effort through a rotary valve in the steering gear. The purpose of power steering fluid is to transmit hydraulic force from the pump to the steering gear, reducing the effort needed to turn the wheels.
Hydraulic Power Steering
Power source: Belt-driven pump
Assist method: Hydraulic pressure
Efficiency: Pump runs constantly, wastes energy
Service: Requires fluid checks and flushes
Failure mode: Whine noise, stiff steering, leaks
Electric Power Steering (EPS)
Power source: Electric motor
Assist method: Motor on column or rack
Efficiency: Motor only runs when needed
Service: No fluid - electronic diagnosis
Failure mode: DTC codes, stiff steering, warning light
Electric Power Steering (EPS)
The type of power steering common in modern vehicles is Electric Power Steering (EPS). EPS uses an electric motor mounted on the steering column or rack to provide assist. The ECU varies the amount of assist based on vehicle speed - more assist at low speeds for parking and less at highway speeds for road feel.
EPS advantages include better fuel economy (no parasitic belt-driven pump), variable assist, and the ability to integrate with lane-keeping and parking assist systems. EPS eliminates the need for power steering fluid, hoses, and pump service.
EPS and ADAS
Electric power steering is required for modern Advanced Driver Assistance Systems (ADAS) such as lane-keeping assist and automated parking. These systems send steering commands through the EPS motor - something impossible with hydraulic systems.
Electric Power Steering (EPS) has largely replaced hydraulic systems in modern vehicles. EPS uses an electric motor, requires no fluid, improves fuel economy, and enables ADAS features like lane-keeping assist.