The quest to enable the compass display in a 2018 Volkswagen Golf Alltrack S led to a deep dive into the erWin service documentation, revealing some intriguing findings about the Vw Compass system. This investigation focuses on the location of the compass antenna and its connection to the car’s infotainment system.
While the documentation doesn’t explicitly identify a dedicated compass antenna, evidence suggests it’s likely integrated into the Roof Antenna (RX5). This antenna, according to schematics, connects to either the Front Information Display Control Head (J685) or the Information Electronics Control Module 1 (J794), depending on the vehicle’s configuration.
In the Alltrack S (base model), these two components (J685 and J794) appear to be combined within the dashboard head unit. This differs from the SE and SEL models, which feature a separate Information Electronics module (J794) housed within the glove compartment CD player unit.
Further investigation revealed a surprising discovery: the Alltrack S has a dummy roof antenna without any wiring. This cost-saving measure seems linked to changes in the 2018 infotainment system, specifically the removal of full VW Car-Net functionality from the S trim.
The wiring diagram also indicates the RX5 antenna’s connection to the Control Module for Emergency Call and Communication Unit (J949), likely associated with Car-Net. This module, located behind the instrument cluster, is the same Telematics module (75-Telematics) that stores GPS data.
Given the absence of the necessary wiring and the lack of a dedicated compass antenna input in the 2018 Composition Color head unit, enabling the compass display via VCDS seems improbable. The missing Car-Net module further eliminates alternative pathways for compass data onto the CAN bus. The possibility of installing the J949 module solely for compass functionality remains a theoretical, yet intriguing, prospect. This investigation highlights the complexities of the VW compass system and the challenges of retrofitting features in modern vehicles.
