T6.1 heated seats, auto headlights and rain sensor failure.

[adman349]

Hi All,

New to the forum so apologies if I've posted this in the wrong area.

Currently having an issue with my T6.1 where the auto headlights, rain sensor and heated seats have all stopped working together.

The only fault I get though OBDEleven is local data bus 4, data message missing.

I’ve booked it into a local garage. They seem to think it is the heated seat module that has failed (though they can’t confirm this without stripping the seats down to get to the module. I’m concerned this might not be the issue as I can’t see how the 3 systems are linked in the wiring diagrams?

Any advice before I spend a lot in labour to have them take a look?

I’ve also checked all fuses and can’t see anything there.

Bit of further info: The issue occurred when starting the van one morning. The only work that I had done on the van recently before this was sound deadening the front doors (about 2 weeks prior). The heated seat light comes on but does not heat up.

Thanks,
Adam

 

[Absolut5]

Hi Adam

There is no module in the seats, the module is behind the centre consul attached to the metal frame. It’s not a place I would be looking first

Any chance you can get a scan using VCDS or similar?

 

[StratosFearXX]

Ugh, no idea but following in case mine does the same.

 

[adman349]

Hi Adam

There is no module in the seats, the module is behind the centre consul attached to the metal frame. It’s not a place I would be looking first

Any chance you can get a scan using VCDS or similar?

The van is with them currently, so can’t get a current scan. I have scanned it with ODBEleven and just got the local data bus 4 missing message in the central electrics module. No other codes. The code is permanently latched as well and will not reset. Tried a bit of digging with ODBEleven but couldn’t get any more data on the fault unfortunately, hence I booked it in (mainly due to lack of time to look at it). When headlights are set to Auto it shows a fault on the MFD ‘Fault: Automatic Headlight Control’

Currently deciding if I should call them on Monday and just get it back and have another look.

Hi All,

New to the forum so apologies if I've posted this in the wrong area.

Currently having an issue with my T6.1 where the auto headlights, rain sensor and heated seats have all stopped working together.

The only fault I get though OBDEleven is local data bus 4, data message missing.

I’ve booked it into a local garage. They seem to think it is the heated seat module that has failed (though they can’t confirm this without stripping the seats down to get to the module. I’m concerned this might not be the issue as I can’t see how the 3 systems are linked in the wiring diagrams?

Any advice before I spend a lot in labour to have them take a look?

I’ve also checked all fuses and can’t see anything there.

Bit of further info: The issue occurred when starting the van one morning. The only work that I had done on the van recently before this was sound deadening the front doors (about 2 weeks prior). The heated seat light comes on but does not heat up.

Thanks,
Adam

Hi Adam

There is no module in the seats, the module is behind the centre consul attached to the metal frame. It’s not a place I would be looking first

Any chance you can get a scan using VCDS or similar?

 

[mmi]

the local data bus 4 missing message in the central electrics module.

G213 rain sensor and J774 heated front seats control unit are members of LIN 4 bus (local data bus) - communicating with the BCM - central electrics.
As the G213 is actually combined rain/light sensor I would expect that fixing the bus issue would solve all the issues at once.

how the 3 systems are linked in the wiring diagrams?

Unfortunately the bus is incorrectly labeled as LIN 2 in below page 51/6 (corrected to LIN 4 in later revisions)

Data Bus Network Wiring Diagram

29 Apr 2020

Current flow diagrams

• Pauly
• current flow diagram transporter t6.1 vw t6.1 wiring diagram
• VW T6.1 Electrical Info

Or in chapter "Networking system" in

SSP 705 - The T6.1 2020

2 Oct 2022

VW Self Study Program

• Pauly
• VW T6 Vehicle Information

 

[adman349]

G213 rain sensor and J774 heated front seats control unit are members of LIN 4 bus (local data bus) - communicating with the BCM - central electrics.
As the G213 is actually combined rain/light sensor I would expect that fixing the bus issue would solve all the issues at once.


Unfortunately the bus is incorrectly labeled as LIN 2 in below page 51/6 (corrected to LIN 4 in later revisions)

Data Bus Network Wiring Diagram

29 Apr 2020

Current flow diagrams

• Pauly
• current flow diagram transporter t6.1 vw t6.1 wiring diagram
• VW T6.1 Electrical Info

Or in chapter "Networking system" in

SSP 705 - The T6.1 2020

2 Oct 2022

VW Self Study Program

• Pauly
• VW T6 Vehicle Information

Thanks really appreciate it. - makes a lot of sense now. Any advice on the best way to diagnose the root cause of the fault with the LIN bus? Is it a physical module or just a connection node under the seat?

 

[mmi]

The bus itself is just a single wire (purple/green) from BCM (T73c/15) which splits (somewhere) into all units on the bus - of course the wire then is part of wiring loom.

I don't think it's under a seat - seems to be straight (without intermediate connectors) connection from BCM to the G213 and J774, as well as the anti-theft alarm sensors G578 (if equipped).


The rain sensor and anti-theft alarm sensor are in rear view mirror base - check the voltage on the bus (about 12V). Also could disconnect one connector at a time to see if it makes a difference (a unit shorting the bus?).

Or simply a fuse??? SC24, SC25, SC55

The only work that I had done on the van recently before this was sound deadening the front doors (about 2 weeks prior)

Does everything in the doors work?

 

[adman349]

The bus itself is just a single wire (purple/green) from BCM (T73c/15) which splits (somewhere) into all units on the bus - of course the wire then is part of wiring loom.

I don't think it's under a seat - seems to be straight (without intermediate connectors) connection from BCM to the G213 and J774, as well as the anti-theft alarm sensors G578 (if equipped).

View attachment 304721
The rain sensor and anti-theft alarm sensor are in rear view mirror base - check the voltage on the bus (about 12V). Also could disconnect one connector at a time to see if it makes a difference (a unit shorting the bus?).

Or simply a fuse??? SC24, SC25, SC55



Does everything in the doors work?

Thanks - yes everything on the doors works fine. When I did the sound deadening I did (stupidly) not disconnect the battery when removing the door ground on the passenger side and heard a click from a module (then disconnected the battery). When I put it all back together everything was fine for about 2 weeks then this happened, so not sure if that could be related or not? Or point to anything?

 

[adman349]

The bus itself is just a single wire (purple/green) from BCM (T73c/15) which splits (somewhere) into all units on the bus - of course the wire then is part of wiring loom.

I don't think it's under a seat - seems to be straight (without intermediate connectors) connection from BCM to the G213 and J774, as well as the anti-theft alarm sensors G578 (if equipped).

View attachment 304721
The rain sensor and anti-theft alarm sensor are in rear view mirror base - check the voltage on the bus (about 12V). Also could disconnect one connector at a time to see if it makes a difference (a unit shorting the bus?).

Or simply a fuse??? SC24, SC25, SC55



Does everything in the doors work?

Only thing I can see linked between the door modules/ground and the systems that have failed is J519 - is it likely the ground fault has damaged the BCM itself?

 

[mmi]

everything was fine for about 2 weeks then this happened, so not sure if that could be related or not?

Just asked to better undestand. The door contollers are also controlled via LIN bus - though a different one (LIN 5) - so there shouldn't be anything common. The buses just connect the BCM in adjacent pins.

Does the van has anti-theft alarm system?

What subsystem does the OBDeleven see?
OBDeleven > Control Units > 09-Central Electrics > Subsystems
Possibly two door controllers "FHSG" but what others?

Any Subsystems seen under 08-Air Conditioning? Well, I'm afraid the OBDeleven quite possibly lacks the capability to see Subsystems in 08?

Anything in History logs about known good - for comparison?

is it likely the ground fault has damaged the BCM itself?

Not likely.
Of course could try to disconnect the battery to reset all the systems and see if things improve.

The rain sensor and anti-theft alarm sensor are in rear view mirror base - check the voltage on the bus (about 12V). Also could disconnect one connector at a time to see if it makes a difference (a unit shorting the bus?).

 

[adman349]

I’ve started having a look at this again today.

Initially checked fuses individually as suggested - no joy. The fault remains the same.

Scanned it again and the two faults are the same (see pictures below). Will continue investigation tomorrow.

Any suggestions on the below:

Looked at the live data, can’t see anything there, unless it looks suspect to anyone?

I’ve also located the BCM to check the bus, whats the easiest way to get a scope on it to check it?

Are the modules J774, G213 and G578 located near the BCM or buried further in the dash?

Thanks again for your help!

 

[adman349]

Just asked to better undestand. The door contollers are also controlled via LIN bus - though a different one (LIN 5) - so there shouldn't be anything common. The buses just connect the BCM in adjacent pins.

Does the van has anti-theft alarm system?

What subsystem does the OBDeleven see?
OBDeleven > Control Units > 09-Central Electrics > Subsystems
Possibly two door controllers "FHSG" but what others?

Any Subsystems seen under 08-Air Conditioning? Well, I'm afraid the OBDeleven quite possibly lacks the capability to see Subsystems in 08?

Anything in History logs about known good - for comparison?


Not likely.
Of course could try to disconnect the battery to reset all the systems and see if things improve.

Yes, it’s got an Anti- theft alarm (it’s gone off on a ferry before )

OBDEleven sees FHSG and DWA

No sub-systems under air-con

No history unfortunately

 

[adman349]

Thanks for your help with this folks - not been able to look at it for a while due to work. Finally found some damaged wires in the interior monitor module. Had some black tape round it, so clearly been out in the past for a repair.

 

[Absolut5]

Thanks for your help with this folks - not been able to look at it for a while due to work. Finally found some damaged wires in the interior monitor module. Had some black tape round it, so clearly been out in the past for a repair. View attachment 306569

Just literally had the exact same fault in , very low mileage t6.1 , with pop top, heated seats not working, but control panel all working, dropped interior light panel, unplug interior sensor plug, wired trapped,

All working now with no faults showing