Quote:
Originally Posted by kamold
Kamold: You always seem to ask the big questions!! :cool:
You are correct in your hypothesis: the management of the multi-function steering wheel module fundamentally changed on MQB platform vehicles - it became directly integrated into the CAN network.
As you have said, the multi-function steering wheel control unit (J453) has traditionally been a LIN slave to the steering column electronics control unit. However, on MQB platform vehicles, J453 is connected to the CAN Gateway module (J533), but it does this still as a LIN slave. I produced the pic below some time ago - it's my feeble attempt at showing the difference in design philosophy:
http://www.vwwatercooled.com.au/foru...EXmN5png-1.jpg
My lay-person understanding (which is of course subject to your advice to the contrary) is that while the CAN network comms happen directly between J453 and the Gateway module, the mechanism for the signal transfers from the multi-function module is still physically transmitted via the coil connectors and the steering column control unit. But I believe that this is done purely for wiring reasons and I suspect that it happens because of the physical closeness of the various components. The wheeling of the CAN wires via J527 has no effect on the steering column module - I think .
Here's how the multi-function module is wired:
http://www.vwwatercooled.com.au/foru...joUR9png-1.jpg
It's not shown in my wiring diagram above, but J453 doesn't have a direct connection to any fuses - it appears to thieve its 12 Volt power from J527 which is itself fused to position #9, or position #41 on the "glove-box fuse panel depending on whether the car was built before/or after Nov 2013.
In terms of Clinton's description of the problem, I will always bow to your more experienced knowledge, but I suspect that it might be prudent to inspect the connectors to the actual buttons and perhaps the connections/wires between J453 and J527 (although it is strange that there are no LIN failure error messages in this case).
Lastly, it would be nice to see the actual error message- at least to determine if J453 is still being registered in the CAN Gateway list, or if the DTC suggests that there is a comms failure problem.
Don
