Understanding Steer-by-Wire Systems and EBS Reset Procedures
When a new steered component is installed, such as an electric power steering (EPS) rack, there is often discussion about the need to train or reset the system for optimal performance. However, understanding this process requires a comprehensive knowledge of modern steering technology. In this article, we will explore the concept of training an EPS rack, self-centering, steering bias, and the setup of the electric steering control system.
Modern Steering Technology Overview
Steering systems have evolved significantly over the years, with hydraulic power steering (HPS) and now electric power steering (EPS) representing the latest advancements. These systems are designed to provide precise and responsive steering, improving both safety and driving experience. However, confusion often arises regarding the need to train or self-center a new EPS rack following installation.
The Misconception of Training an EPS Rack
Historically, training a steering component was a concept associated with hydraulic systems, where the gearing and alignment were adjusted to provide the correct initial turning position. However, in modern EPS systems, there is no training involved in the traditional sense. Here's why:
Self-Centering and Alignment Geometry
The self-centering of a steering wheel is achieved through alignment geometry, not the steering rack or gear assembly. The angles at which the wheels are positioned ensure that when the steering wheel is centered, the vehicle naturally aligns itself. This alignment is precisely set during the vehicle's factory assembly and does not require any additional procedures or training.
Steering Gear Bias and Factory Calibration
In hydraulic power steering systems, steering gear bias is typically balanced during the factory calibration process. Similarly, in EPS systems, the torque sensor is also factory calibrated and set to ensure proper assistance and feedback. In many vehicles, especially those with column assist EPS, the torque sensor and assistance motor are placed under the dashboard, and the factory ensures that these components are correctly calibrated.
For pinion assist or rack assist EPS systems, the torque sensor is typically part of the gear assembly. As such, the factory also balances this sensor during the production process. Therefore, in these systems, there is no need for additional calibration or training.
User-Adjustable Steering Modes
Some modern vehicles offer user-adjustable steering modes, such as sport, normal, or light, which can be accessed through the steering wheel controls. These modes adjust the gain of the torque sensor amplifier to change the steering feel. However, this adjustment is a one-time setting made by the manufacturer and does not require ongoing training or re-adjustment.
Addressing Misaligned or Faulty Steering Components
If a fault is detected in the steering or the car is turning towards one side, it could be due to several factors, such as misaligned wheels or a potential fault in the steering gear. If a newly installed EPS rack is behaving abnormally, these issues should be addressed by checking the wheel alignment and inspecting the steering gear for any signs of damage or malfunction.
Resetting the Electric Steering Control System (EBS)
In some cases, if the EPS rack is not functioning as expected, it may be necessary to reset the electric steering control system (EBS) to ensure proper operation. This procedure is typically performed with the help of an OBD-II diagnostic tool. A professional wheel alignment specialist should have access to this tool and can set the zero point for the angle sensor. This ensures that the EBS computer can accurately determine the trajectory of the vehicle if a skid occurs.
Conclusion
In summary, when installing a new EPS rack, there is no need to train the system as there was in older hydraulic systems. Self-centering is achieved through alignment geometry, and the factory ensures that the torque sensor and assistance motor are calibrated for optimal performance. User-adjustable steering modes are also a one-time setting for the driver's convenience. If there are issues with the steering, professional inspection and adjustment may be necessary, but the system itself does not require additional training. For more detailed procedures, an OBD-II diagnostic tool can assist in resetting the EBS control system.