Module 3G0998478A: Control unit for the LED cornering light of the right headlight

The module with part number 3G0998478A is an electronic control unit for the LED cornering light , specifically designed for the right front headlight of vehicles such as the Volkswagen Passat B8 . In simpler terms, it is the "brain" that manages the operation of the light that turns on to illuminate the inside of a bend when the steering wheel is turned at low speed.

This feature, also known as cornering light or part of the Adaptive Front-Lighting System (AFS), significantly improves visibility and safety when driving at night or in low-light conditions by illuminating areas that would otherwise remain dark during turning maneuvers.

Why Do You Need to Replace It?

This module needs to be replaced when it stops working properly, causing the cornering light to malfunction. The main reasons for replacement include:

• Turn Signal Light Failure: The most obvious symptom is the failure of the right turn signal light to illuminate when the steering wheel is turned to the right. The left turn signal light may still work properly.

• Dashboard Error Message: A fault with the 3G0998478A module often activates a fault indicator light on the instrument cluster. The message may vary, but typically indicates a problem with the adaptive lighting system (e.g., "Adaptive Lighting System (AFS) Fault").

• Internal Electronic Damage: Like any electronic component, the module can suffer damage from power surges, moisture ingress into the headlight, or simply from the normal deterioration of its components over time.

• Communication Problems: The control unit may no longer be able to communicate properly with other vehicle systems, such as the steering angle sensor or the main on-board network control unit, thus preventing the cornering light from activating.

In summary, if the right-hand cornering light on your Passat B8 is not working and there is a warning on the dashboard regarding the lighting system, it is very likely that the 3G0998478A module is faulty and needs to be replaced to restore full functionality and safety to the vehicle.

Replacing this module is often a cheaper solution than replacing the entire headlight, as the headlight itself may be intact but not working due to the failure of this specific electronic component. Many replacement parts are "plug & play," meaning they can be installed without significant modifications to the vehicle's original wiring.