Electric power steering (EPS) malfunctions can pose a serious safety risk. This article examines a Mercedes-Benz power steering recall due to faulty welding in the EPS control unit, exploring the defect, safety risks, causes, and corrective actions taken.
Understanding the Mercedes-Benz Power Steering Recall
In 2017, Mercedes-Benz issued a recall for certain Metris (VS20 – model series 447) and C-Class vehicles due to a potential power steering malfunction. The recall stemmed from a manufacturing defect in the electric power steering (EPS) control unit. Improper welding of contact pins within the unit could lead to a loss of electrical connection, causing the power steering assist to deactivate unexpectedly.
The Safety Risk of a Power Steering Malfunction
A sudden loss of power steering assist can significantly increase the risk of an accident. Without power steering, the driver needs to exert considerably more effort to steer the vehicle, especially at lower speeds. This can make it difficult to control the vehicle and increase the risk of a collision. The unexpected nature of the malfunction further amplifies the danger.
Root Cause Analysis: Faulty Welding Process
Investigations revealed that a process deviation at the supplier’s manufacturing facility was the root cause of the defect. The optically guided laser welding machine used in the production of the EPS control units had a technical weakness. Due to light refraction and mirroring effects, the camera system could incorrectly identify the outer edge of the contact pins as the welding zone. This resulted in insufficient welding, jeopardizing the electrical connection. Furthermore, an automatic position and path control system for the laser was not implemented, exacerbating the issue.
Identifying Affected Vehicles and Implementing Corrective Actions
Upon receiving a report of a defective steering rack in a C-Class vehicle in March 2017, Mercedes-Benz (DAG) initiated an investigation. The supplier conducted a root cause analysis, confirming the faulty welding as the culprit. Corrective actions were swiftly implemented, including the installation of a laser position monitoring system in late May 2017. A review of production records identified additional potentially affected control modules.
By August 2017, affected Mercedes-Benz Metris vehicles were also identified. In September 2017, DAG issued the recall, acknowledging the potential safety risk. The supplier modified the production process, implementing an automatic laser position and path control system and improving light conditions. These changes, effective from June 1, 2017, ensured that the defect would not occur in subsequently manufactured parts. The recall affected a small number of vehicles with an estimated 100% defect rate.
Conclusion: Addressing the Power Steering Malfunction
The Mercedes-Benz power steering recall highlights the importance of robust quality control processes in automotive manufacturing. The prompt investigation, corrective actions, and recall demonstrate a commitment to safety. If you own a Mercedes-Benz vehicle and suspect a power steering issue, consult a qualified technician or contact your local Mercedes-Benz dealership for further assistance.
