[T6] Looking for the D+ signal wire in a T6
- Thread starter Bryn23
- Start date
May need some help here. I've attached a pdf (hopefully it's readable) it's a picture of the only electrical object I can see under the seat. No corresponding details to that on the schematic?? If you could pm me your number I'd appreciate a chat over the phone. Thanks
That module is a Headlight Range control module if this is correct, VOLKSWAGEN 7P6 907 357 E / 7P6907357E T-Cross (C11) 2019 Light Module ECU
But what are you looking for under the driver's seat (LHD or RHD)?
The BCM is under the dash.
Ah have you fallen into the LHD / RHD pit? Factory wiring diagrams refer to LHD vehicles where the driver sits on the left!
It's all there to confuse those few parts of the world that drive on the left and have the driver sitting on the right!
... Pmsl I reckon so... I'll have another go tomorrow night. Thanks mate
Then you have lost me, it sounds as though they moved it for a 6.1
The latest information (2019) in the downloads section mentions the J7 relay under the seat etc. I may see if I can cobble something up using a delay on timer, just to keep the extra demand out of the way for starting and use the ignition on signal. Plenty of people seem to be using this ignition on rather than engine running method. Someone mentioned earlier in the thread that most leisure battery management systems detect low voltage and cease to draw current. Pity, for me the engine running signal was definitely the 'best practise' approach.
Thanks again for your help and everyone else.
Thanks again for your help and everyone else.
Hi Dell, my 6.1 hasn't got the J7 relay etc under the left hand seat.The T6 "Engine Run" feed from the BCM is shown here:
+12v switched on when RPM engine run is detected.
used by the OEM setup to switch a 80A relay that connects the second battery (old skool SCR)
View attachment 70918
Could you tell me where the contacts you've illustrated are to be found please? I've downloaded the drwg and it says T73a is a 73 pin connector but not where you can find it.
Thanks
The 73 pin connector is one of three? connectors plugged into the BCM which is located under the dash near the steering column on a RHD T6. It's in a very inaccessible location and is almost invisible even with the under dash plastic coverings removed.
That's the T6 diagram?
For a T6.1 you want this one:
This thread shows you what you should find with a factory Second battery:
www.t6forum.com
T6.1 factory aux battery split charge relay upgrade & solar panel install.
Hi, I had the factory fitted aux battery ( under a single seat with swivel base ) fitted to my T6.1 with the intention of using it as a camper leisure battery. After getting less than impressive performance and reading about how the split charge relay is a pretty bad charging method I wanted to...
Yeah I'd downloaded the 6.1 dwg too. They both reference a J7 battery etc, under the LHS seat. Mine has none of this wiring.
So the question remains: where should I pick a signal up for engine running rather than ignition on?
Appears to me, to require hunting out the 70+ contact plug and possibly programming the OP with a VDS setup?
So the question remains: where should I pick a signal up for engine running rather than ignition on?
Appears to me, to require hunting out the 70+ contact plug and possibly programming the OP with a VDS setup?
Hi @radfraz as I've said before, the J519 is up under the dash with more than one 73 pin plug in it. It is most likely that 73b/58 is an empty chamber in that plug so will need the correct connector inserting into it with the control wire attached. There is a VW supplied 'repair wire' which is simply a length of yellow wire with the connectors ready attached to each end, you cut it where convenient to connect to your signal wire to the DC-DC device. I can't find the part number for this at present but someone will come along with it I have no doubt.
Then as you say the BCM has to ne coded to enable 'Battery Isolation'. If it helps I can do that for you when the time arises (if I'm in the UK at the time).
@radfraz if you don't have an existing factory second battery them you will not have any of the wiring under the seats.
If you are retrofitting then removing the BCM connector, pinning it up and then coding everything up in VCDS is the gold standard of doing it but not necessary.
You can get 99% the same behaviour by just picking up 12v on an ignition switched circuit in the dash fusebox using a fuse tap much much easier.
Only difference will be that the BCM signal will not be live if you are in the habit of turning the ignition on but not starting the engine. It can also so some load shedding during start/stop cycles.
But most people do it, including converters, and it works just fine.
If you are retrofitting then removing the BCM connector, pinning it up and then coding everything up in VCDS is the gold standard of doing it but not necessary.
You can get 99% the same behaviour by just picking up 12v on an ignition switched circuit in the dash fusebox using a fuse tap much much easier.
Only difference will be that the BCM signal will not be live if you are in the habit of turning the ignition on but not starting the engine. It can also so some load shedding during start/stop cycles.
But most people do it, including converters, and it works just fine.
@rod_vw & @roadtripper thanks very much for this, sorry if it's been harder work than it should have been getting the facts across. I get it now (I think )
I think I'll go ignition signal to get me away quickly.... I've not used the bloody van yet and bought it at Christmas! My reservations about this are that the power bank I'm using is a Clayton 2500 and will pull the best part of 50a if it's battery has been depleted.However, I think that as soon as it senses the voltage drop caused by the starter turning it'll stop drawing current?
I do intend to go engine running signal. I'll be in touch when I've got the hardwiring sorted Rod.
Thanks again fellas, have a great BH weekend.
Fraz
I think I'll go ignition signal to get me away quickly.... I've not used the bloody van yet and bought it at Christmas! My reservations about this are that the power bank I'm using is a Clayton 2500 and will pull the best part of 50a if it's battery has been depleted.However, I think that as soon as it senses the voltage drop caused by the starter turning it'll stop drawing current?
I do intend to go engine running signal. I'll be in touch when I've got the hardwiring sorted Rod.
Thanks again fellas, have a great BH weekend.
Fraz
If you're concerned about that you can always put a switch in the signal line that means you could disable it if you were concerned about starting.
Keep in mind that a heated windscreen takes 40A each side, the 6.1 is a much more electrical centric beast, mine has 250A alternator. You may also find you can downrate your charging in the Clayton to something like 30A, which might be kinder to it's batteries long term.
Keep in mind that a heated windscreen takes 40A each side, the 6.1 is a much more electrical centric beast, mine has 250A alternator. You may also find you can downrate your charging in the Clayton to something like 30A, which might be kinder to it's batteries long term.
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