In my 2010 T5GP the textured surface on my plastic steering wheel had started to peel so I decided to replace it with a MFSW (leather wheel with controls for radio and dash built in).
What I've done
On the MFSW the horn and left hand radio buttons work but the right hand buttons don't. The up and down buttons should scroll the MFD (trip computer) but they do nothing.
I already have the toggle switch on the wiper stalk to control my midline MFD (hence the code for MFD being already set). The wiper stalk switches work fine.
How I think it works
It seems the MFD is controlled directly from the wiper stalk switches via three wires. These run direct from the switches on the wiper stalk to the instrument panel J285.
The MFSW does its stuff via the single wire LIN bus (the extra wire I installed from slip-ring pin10 to BCM plug pin17). The BCM converts the LIN bus signals to two wire CAN bus and sends the message on to the radio and instrument panel. With MFSW the horn is also controlled via the LIN bus, the BCM sending 12v to the horn when instructed to via the LIN bus. In T5GPs without MFSW a switched earth control's the BCMs horn function.
Possible cause of problem
The T5GP never came as standard with both multifunction wiper stalk and MFSW. It was one or the other (or neither if you had lowline dash with no MFD). So the Instrument cluster is seeing the signal on the three wires from the wiper stalk and ignoring the CAN bus signal:-
So I tried replacing the wiper stalk for one without the multifunction switch but the problem persists.
The MFSW is faulty:-
So I've tried three different MFSWs and they all have the same problem. All from Mk6 Golfs and look identical to the wheel factory fit in a T5GP.
The airbag harness is faulty (though unlikely it would only affect the right hand switches):-
So I've tried two different harnesses and they both have the same problem.
The BCM isn't the right spec and is not converting the LIN bus signal and forwarding the info to the dash:-
So why is it doing it for the horn and radio? Could you spec for MFSW with left hand buttons only?
The midline dash isn't up to spec and can't be controlled via MFSW CAN bus:-
I'm sure I've read of others doing this with midline dashes.
There could be a missing coding option to tell the MFD to work from the MFSW and not the wiper stalk?
I don't think this is likely. Why would the option be there if the vehicles never come from the factory in that configuration.
Current situation
I'm out of ideas. I have the wiring diagrams for the van and I have triple checked everything I can think of. I know it is a really trivial problem and getting the rhs MFSW switches working adds no functionality, but I would like to get to the bottom of this.
Any advice would be greatly appreciated. T:
Here is a VCDS scan of the relevant units:
What I've done
- installed the MFSW
- changed the airbag loom
- coded 'MFSW installed' in Address 09: Cent. Elect. (J519)
- coded for 'MFD' in Address 17: Instruments (J285) (this code was already set)
- added two repair wires for MFSW according to wiring diagrams
- slip-ring (F138) pin9 to ignition live
- slip-ring (F138) pin10 to Cent. Elect. aka BCM (J519) white plug pin17 (LIN).
On the MFSW the horn and left hand radio buttons work but the right hand buttons don't. The up and down buttons should scroll the MFD (trip computer) but they do nothing.
I already have the toggle switch on the wiper stalk to control my midline MFD (hence the code for MFD being already set). The wiper stalk switches work fine.
How I think it works
It seems the MFD is controlled directly from the wiper stalk switches via three wires. These run direct from the switches on the wiper stalk to the instrument panel J285.
The MFSW does its stuff via the single wire LIN bus (the extra wire I installed from slip-ring pin10 to BCM plug pin17). The BCM converts the LIN bus signals to two wire CAN bus and sends the message on to the radio and instrument panel. With MFSW the horn is also controlled via the LIN bus, the BCM sending 12v to the horn when instructed to via the LIN bus. In T5GPs without MFSW a switched earth control's the BCMs horn function.
Possible cause of problem
The T5GP never came as standard with both multifunction wiper stalk and MFSW. It was one or the other (or neither if you had lowline dash with no MFD). So the Instrument cluster is seeing the signal on the three wires from the wiper stalk and ignoring the CAN bus signal:-
So I tried replacing the wiper stalk for one without the multifunction switch but the problem persists.
The MFSW is faulty:-
So I've tried three different MFSWs and they all have the same problem. All from Mk6 Golfs and look identical to the wheel factory fit in a T5GP.
The airbag harness is faulty (though unlikely it would only affect the right hand switches):-
So I've tried two different harnesses and they both have the same problem.
The BCM isn't the right spec and is not converting the LIN bus signal and forwarding the info to the dash:-
So why is it doing it for the horn and radio? Could you spec for MFSW with left hand buttons only?
The midline dash isn't up to spec and can't be controlled via MFSW CAN bus:-
I'm sure I've read of others doing this with midline dashes.
There could be a missing coding option to tell the MFD to work from the MFSW and not the wiper stalk?
I don't think this is likely. Why would the option be there if the vehicles never come from the factory in that configuration.
Current situation
I'm out of ideas. I have the wiring diagrams for the van and I have triple checked everything I can think of. I know it is a really trivial problem and getting the rhs MFSW switches working adds no functionality, but I would like to get to the bottom of this.
Any advice would be greatly appreciated. T:
Here is a VCDS scan of the relevant units:
Code:
-------------------------------------------------------------------------------
Address 09: Cent. Elect. (J519) Labels: 7H0-937-08x-09.clb
Part No SW: 7H0 937 087 B HW: 7H0 937 087 B
Component: BCM T5GP H+4 H46 0207
Revision: BO046001 Serial number: 0156 071100025
Coding: A0A0203A0E612421802840007C2B8C500080430F60860000300000000000
Shop #: WSC 02736 790 12345
VCID: 3365EF1592FA0186591-8066
Subsystem 1 - Part No SW: 7E0 959 801 C HW: 7E0 959 801 C Labels: 7E0-959-801.CLB
Component: J386__TSG_FT 003 3310
Coding: 050000
Subsystem 2 - Part No SW: 7E0 959 802 C HW: 7E0 959 802 C Labels: 7E0-959-802.CLB
Component: J387__TSG_BT 003 3310
Coding: 040000
Subsystem 3 - Part No: 1K0 951 605 C
Component: LIN BACKUP HO H05 1501
Coding: 000000
Subsystem 4 - Part No SW: 3C8 959 537 D HW: 3C8 959 537 D Labels: 3C8-959-537.CLB
Component: E221__MFL-TK6 0022
Coding: E20000
No fault code found.
-------------------------------------------------------------------------------
Address 17: Instruments (J285) Labels: 5K0-920-xxx-17.clb
Part No SW: 7E0 920 960 A HW: 7E0 920 960 A
Component: KOMBI H16 0111
Serial number: 00000000000000
Coding: 460A00
Shop #: WSC 02736 790 50316
ASAM Dataset: EV_Kombi_UDS_VDD_RM09 A04041
ROD: EV_Kombi_UDS_VDD_RM09_SE35.rod
VCID: 275D0B455E227D26F59-8072
No fault code found.
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