The automotive diagnostic landscape changed significantly around 2008 with the introduction of UDS (Unified Diagnostic Services) and ODX (Open Diagnostic Data Exchange) protocols. Vehicles like the Audi A4/A5 (8T/8K) were among the first to adopt this new standard, impacting how diagnostic tools like VCDS Ross-Tech interact with vehicle control modules. This article explores the key differences between pre-UDS and UDS systems and explains how VCDS Ross-Tech addresses the challenges posed by these newer protocols.
Before UDS, diagnostic trouble codes (DTCs) and measuring blocks followed a more standardized format. For instance, fault code 00532 consistently indicated “Supply Voltage B+: Signal too Low” across various Volkswagen Group vehicles. This allowed scan tools to interpret fault codes without specific vehicle information. UDS changed this by introducing a manufacturer-specific translation layer.
The shift to UDS stemmed from a collaborative effort by European automakers and suppliers to establish a common diagnostic language (ISO 15765). While intended to streamline diagnostics, it inadvertently created a significant hurdle for scan tool developers. Instead of universal interpretations, UDS requires unique translation files, known as ROD (ODX) files, for each specific control module. This necessitates VCDS Ross-Tech to maintain an extensive database of ROD files to ensure compatibility across different vehicle models and control units.
When using VCDS Ross-Tech with a UDS-compliant control module, the interface will display “Protocol: UDS.” Traditional functions like Measuring Blocks are replaced with Advanced Measuring Values. This functionality allows users to select specific parameters to measure from a predefined list within the ROD file:
Accessing Advanced Measuring Values requires the corresponding ROD file for the specific control module. If the button is grayed out, it indicates a missing ROD file. In such cases, ensure you are using the latest version of VCDS Ross-Tech: http://www.ross-tech.com/vcds/download/. Beta versions, if available, often include the most up-to-date ROD files: http://www.ross-tech.com/vcds/download/beta/current.html.
If the issue persists after updating VCDS Ross-Tech, and you encounter a message like ‘ No ASAM data for: “EV_ECM14TFS01104E997016B” (VW37) ‘, providing an Auto-Scan to Ross-Tech is crucial. While previously, users could submit PLA and PLB files for missing label files in pre-UDS systems (http://wiki.ross-tech.com/wiki/index.php/Control_Module_Maps), this is not possible with UDS. Since a ROD file is necessary to interpret any data from the control module, an Auto-Scan from http://www.ross-tech.com/vcds/tour/main_screen.html is the only way to assist Ross-Tech in adding support for the missing module.
UDS modules still utilize label files for functions like Coding and Security Access. If a UDS module lacks a label file, similarly, an Auto-Scan, not PLA or PLB files, is required to aid Ross-Tech in developing the necessary label file. The complexities of UDS and ODX necessitate a different approach to troubleshooting and supporting these newer vehicle systems, relying heavily on Auto-Scans and continuous updates to the VCDS Ross-Tech software and its database of ROD files.
