Retrofitting a multifunction steering wheel (MFSW) in a VW T5 can significantly enhance the driving experience. However, the process can be complex, and coding issues can arise. This article addresses a common problem encountered after an MFSW retrofit in a VW T5, focusing on VCDS coding and potential solutions.
Understanding the Problem: Partial MFSW Functionality
A VW T5 owner successfully installed a new MFSW, including the necessary wiring and harness. Following the retrofit, the horn and button illumination function correctly. The dashboard display now shows trip computer information like consumption and speed, controllable via the up, down, and OK buttons. However, other MFSW buttons remain unresponsive and are not recognized in VCDS. This indicates that the MFSW is partially functional, acting more like a stalk with limited button controls.
Potential Causes and Solutions using VCDS
Several factors can contribute to this issue, often related to Vcds Mfsw Coding:
1. Incorrect Coding in BCM
The Body Control Module (BCM) plays a crucial role in managing the MFSW functionality. Verify that the correct coding for MFSW is activated in the BCM. Using VCDS, navigate to the BCM module (typically address 09). Check the long coding and ensure that the bits related to MFSW are enabled. Refer to the VW T5 specific coding documentation or online forums for the correct coding values. Commonly, this involves enabling bits related to steering wheel buttons and multifunction display. A single incorrect bit can lead to partial or no functionality.
2. Steering Wheel Module Coding
The steering wheel module itself (Address 09 – Subsystem 3 in the provided autoscan) requires proper coding. The autoscan indicates a coding of “E20000” for this module (Component: E221__MFL-TK6). This coding needs to be verified against known good values for the specific steering wheel module installed. Incorrect coding here can prevent button recognition and functionality. Consult your vehicle’s specific documentation or resources like online forums dedicated to VW coding.
3. Compatibility Issues
While the new steering wheel might be from a similar-age Golf, subtle compatibility differences can exist between models. Ensure the chosen steering wheel and control module are fully compatible with the T5’s BCM and other systems. Check part numbers and revisions to confirm compatibility. Research online forums for documented successful retrofits with the specific components used.
4. Wiring Harness Issues
Double-check all wiring connections, especially those related to the MFSW buttons. A loose connection or incorrectly pinned wire can disrupt communication between the steering wheel and the BCM. Refer to wiring diagrams for your specific T5 model year and compare them to your installation. Pay close attention to CAN bus connections, as they are critical for MFSW operation.
5. CAN Bus Communication Problems
The MFSW communicates with the BCM via the CAN bus. Any issues within the CAN bus system can affect functionality. Check for any fault codes related to CAN communication in the autoscan. The provided autoscan does show a fault code in the CAN Gateway (Address 19): “01304 – Radio 004 – No Signal/Communication”. While this may be related to the aftermarket radio, it’s crucial to rule out any underlying CAN bus issues that could also be affecting the MFSW.
Conclusion: Diagnosis and Next Steps
Resolving partial MFSW functionality requires meticulous troubleshooting. Carefully review the VCDS coding in both the BCM and steering wheel module. Verify component compatibility and inspect all wiring connections. Address any CAN bus related fault codes. If the problem persists, consult with a specialist in VW diagnostics and coding for further assistance. A thorough examination of these areas will likely pinpoint the cause and lead to a fully functional MFSW.
