This article explores VCDS modifications for a 2011 European Passat Highline (3C/B7 Variant 365) equipped with bi-xenon and LED lights. The goal is to customize the automatic headlight control to utilize LED DRLs during daylight and activate bi-xenon only when necessary.
The owner has successfully coded “Coming Home” and “Leaving Home” functions to use fog lights instead of xenons to prolong bulb life. Currently, in “Auto” mode, the xenon headlights remain on constantly. The desired outcome is to have full brightness front and rear LED DRLs active during daylight hours, with xenons engaging automatically at dusk.
The primary area of investigation within VCDS is “09 Cent. Elect.” However, numerous undocumented bits in the long coding helper make experimentation risky. The question arises whether the desired functionality can be achieved through these undocumented bits or potentially within “Byte 18.” Research into this specific Passat model has been challenging due to its limited prevalence, particularly in the US market.
The provided Auto-Scan reveals a fault code in module 09 – Cent. Elect.:
01800 - Light Switch (E1) 008 - Implausible Signal - Intermittent
This fault may be related to the light switch or wiring and could potentially influence the coding process. While this error doesn’t directly address the bi-xenon control, resolving it might be beneficial.
Addressing the core issue of bi-xenon control, potential solutions lie within the long coding of module 09 – Cent. Elect. Specific bytes and bits related to daytime running lights and headlight activation need to be identified. Community forums dedicated to VCDS and Volkswagen models could offer valuable insights from users with experience modifying similar vehicles. Sharing the discovered undocumented bits might also contribute to collective knowledge.
Further investigation should focus on decoding the long coding structure for module 09. Resources such as the Ross-Tech Wiki and online forums dedicated to VCDS tuning can provide guidance. Caution is advised when modifying undocumented bits, and it’s recommended to document any changes meticulously.
Ultimately, achieving the desired bi-xenon control behavior in the Passat 3C requires a deep understanding of the vehicle’s coding structure. Leveraging community resources and proceeding cautiously with undocumented bits are crucial for successful modification.
