Copyright by Hyundai Motor Company. All rights reserved. EHPS

2 Comparison ItemHydraulic Power SteeringElectronic Hydraulic Power Steering Layout System Energy resources from engine crankshaft (Power steering pump) Energy resources from vehicle battery (Electric motor drives the power steering pump) Benefit & Demerit Relatively lower cost and weight Pumping at all times even if not steered poor NVH Better fuel consumption Energy save (motor speed control) Lower NVH Variable steering effort upon condition Relatively higher cost

3 EHPS Layout Reservoir hose Remote reservoir MPU assembly Pressure line Return line Gear box Lower of engine room (RH)

4 EHPS Operating principle Steering wheel Rack & Pinion Cylinder - + Hydraulic control valve Pressure line Return line Pump Motor M Steering angle velocity ECM Vehicle speed - Input signals to EHPS control module: Vehicle speed, Steering angle velocity, Engine speed - Vehicle speed & Steering angle speed change Motor Control Map (ECM) Pumping flow & pressure changed Hydraulic control Valve Steering effort changed. Reservoir tank

5 EHPS Component – MPU (Motor Power Unit) Reservoir Tank (Oil storage) Gear pump Control module (embedded in MPU) Connector A Motor (Drives pump) - 710W / 85A (Max) Cover (for ECM protection & lower NVH) Connector B A1(M+)A2(M-) CAN_H CAN_L IG N.A Oil flow Connector layout

6 EHPS System control Steering angle speed (°/s) Motor speed / (1/min) Motor rotates with 2,000rpm if vehicle stops and not steered. As the vehicle speed increases, motor speed drops up to a half. VS / (km/h) When the vehicle speed is high, motor speed reduces for higher steering effort. If steering angle speed is high, motor speed increases proportionally to offer lower steering effort.

7 EHPS Diagnosis Gentle steering (VS=0kph, idle eng. Speed)

8 EHPS Failsafe LevelDescriptionRelated failure 1 System control totally stops and MPU must be replaced. Temperature sensor failure Control module hardware error 2 Manual steering only available. Cannot be restored in the current driving cycle. Motor fault – not running Motor over current Motor temperature high 3 Manual steering only available but restores immediately in the current driving cycle. Battery voltage is too high or low Control module temperature high Motor temperature low 4 Electronic steering is available partially. Steering angle sensor circuit CAN timeout (EMS) CAN timeout (SAS) Invalid engine speed (EMS) Invalid vehicle speed (EMS)