Three facts about modern electric power steering

Three facts about modern electric power steering

EPS has enabled key vehicle advancements like stop/start systems, hybrids and advanced driver assistance features or ADAS.

For over 20 years, electric power steering or EPS has been a solution first adopted in smaller cars but now is the “go-to” steering assist technology for trucks, large sedans and EVs. EPS has enabled key vehicle advancements like stop/start systems, hybrids and advanced driver assistance features or ADAS. Let’s explore three important facts about the evolution of modern EPS systems.

EPS has also seen significant improvements over the years. Early systems often overheated during extended parking maneuvers, and many drivers disliked the altered steering feel. Modern systems, however, have been refined to the point where they can even steer the vehicle autonomously.

The biggest change has been in the electric power steering control module’s connection with the vehicle.

Fact number one – the EPS control module is part of the vehicle’s Hi-speed CAN bus, communicating with modules like the engine control unit, ABS and body control module. This integration allows the sharing of data like vehicle speed, steering angle and engine operation between systems. The EPS can even work with stability control to apply brakes and steer the vehicle. The shared data can solve mechanical problems like torque steer experienced by front-wheel-drive vehicles and even pulls due to road crown or misaligned toe.

Fact number two – EPS systems can’t be fixed simply by replacing parts. The rack and module can be very expensive to replace, and steering angle and torque sensors are difficult to swap due to their location on the steering column.

The best diagnostic approach is to examine the inputs, codes and network using a scan tool before conducting a physical inspection of the components. It’s important to review the data from the sensors to ensure they are not providing the wrong information. Additionally, check the other modules on the CAN bus to confirm they are communicating. Missing data, such as vehicle speed or yaw, can cause the system to enter a fail-safe mode.

Fact number three – EPS systems use a brushless electric motor, powered by a 9- to 16-volt signal, to move in both directions. A rotational sensor determines the motor’s position. If the module is replaced or the toe adjusted, the steering system’s end stops must be relearned to prevent overextension, in addition to calibrating the steering angle sensor.

The motor can be attached to the steering rack or column, with many modern vehicles having it mounted to the base of the steering gear on the rack. It connects using a screw-like mechanism or a high-strength belt.

The motor is generally non-serviceable, with gear lash and belt tension set at the factory. Removing the motor may also void the core charge.

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