Factory Aux Battery Relay T6

[Dans_t6]

Gday from down under

Does anyone know if a faulty aux battery relay from factory would cause the battery light illuminate on the dash. When it does do this I can hear the relay tick as the light comes on.
After starting the van, about 30 seconds later the battery light comes on which as a result causes the alternator to disengage leaving the batteries not being charged and eventually going flat.
I’m assuming there’s a possibility that the alternator has died but the fact that it takes 30 secs to 1 min for it to disengage, that it might be another cause. Certainly one that’s not as expensive and a pain in the arse to change.
I have replaced the starter battery and have had VW code a new battery but am still having the same problem.
Any help or advice, other than having VW charge me a fortune to try diagnose, is much appreciated

 

[roadtripper]

What fault codes are logged?

 

[Dellmassive]

Not likely.

The engine-run signal for the battery relay comes from the BCM.

The alternator output is failing..... so the light is switched on and the BCM then shuts off power to the SCR.

There is a LIN bus wire from the batter NEG shunt to the Alternator, that has been known to break.

Or possibly alternator problem.

Or belt issues.

As above a code scan may offer some direction.

Got any pics of the van and battery.... Is it a T6, what's year.?

 

[Dans_t6]

Thanks for the advice so far.
Vehicle is as follows:
VW TRANSPORTER T6 SFD,SFE,SFL,SFZ,SJD,SJE,SJL,SJZ Platform/Chassis 2.0 TDI 4motion Diesel 2016
I have purchased a new belt which I will fit in the morning. Unfortunately I don’t have a scanner on hand to see logged codes. I will grab one tonight to see what codes it’s spitting out. I had it at VW this morning to code in the new battery but they did not tell me any further codes. But I guess they normally wouldn’t share that info with me anyway.
I have read about the LINBUS wire and will also be checking that tomorrow morning. Is there an easy way of checking the wire without too much disassembly? From underneath the ac compressor is pretty much in the way of the alternator.
I’m hoping it’s not an alternator issue as down here in Australia, a replacement one will set me back about $950 (£490).
I’ll drive to get my scanner now and post error codes soon.

 

[Dans_t6]

I have a very very basic scanner and it pumps out no error codes. It has picked error codes up in the past so I know it can do it.
Think I need to invest in a OBDEleven scanner…..

 

[Dans_t6]

Update……
Fitted new belt…..Unfortunately didn’t fix.
Next testing of LINBUS wire……perfect continuity. Certainly a pain in the bum to disconnect from alternator end.
And what I didn’t want to do…….remove alternator. And wasn’t that fun.
Once out, removed voltage regulator and brushes. Brushes completely worn out.
Found a way to replace brushes as availability of regulator and brush assembly not so easy to get here in Aus.
Put it all back together.
Battery light no longer coming on but alternator not charging. 12.2v at battery.
Now at a loss
Do I need to get anything recoded??
Any direction much obliged.

 

[roadtripper]

You need to see what (if any) faults are being logged. If you can't see what the electronics are seeing you are working in the dark.

 

[Dans_t6]

You need to see what (if any) faults are being logged. If you can't see what the electronics are seeing you are working in the dark.

Fair call.
I have a cheap scanner but it wasn’t seeing any errors. Might not be smart enough to.
Will have to take it to a VW specialist I think. Or if I purchase a OBDeleven would that enable me to pull error codes and or modify codes??

 

[roadtripper]

Carista / OBD11 / VCDS are the popular options around these parts.

If you are into serious coding then VCDS is as close as you're going to get to official and it's also really the only option if you have a knarlly issue that needs to capture real time data.

But for basic fault code work the basic Carista is cheap and capable and will probably pay for itself in saving diagnostic costs.

 

[Dellmassive]

@Loz has added the new download.

T6 - Alternator removal and maintenance

Alternator removal and maintenance section from the workshop manual

www.t6forum.com

.

 

[Dellmassive]

as the battery was disconnected the van will go into relearn for the battery state.

try running the engine . . . then turn on all the electrical loads.

that should make the alternator voltage rise to 13.8v or more.


also a quick tip to try is to disconnect the LIN Bus from the battery post for a few mins - the idea being that if the van cant detect the battery current it will default to a fall back measure fix voltage of 13.2v.




got some more pics. . . . ? of the batterys and monitors etc.

#
gota say i love the AUZ van styles and layout - solar kings and lovers of the SB50 connectors lol ( for EVERYTHING !!)

Love REDARC stuff too. . .

 

[Dans_t6]

as the battery was disconnected the van will go into relearn for the battery state.

try running the engine . . . then turn on all the electrical loads.

that should make the alternator voltage rise to 13.8v or more.


also a quick tip to try is to disconnect the LIN Bus from the battery post for a few mins - the idea being that if the van cant detect the battery current it will default to a fall back measure fix voltage of 13.2v.




got some more pics. . . . ? of the batterys and monitors etc.

#
gota say i love the AUZ van styles and layout - solar kings and lovers of the SB50 connectors lol ( for EVERYTHING !!)

Love REDARC stuff too. . .

All attempts to get the alternator to kicking so far has failed.
Running and driving of car with all electrical loads on, no change
Disconnected linbus wire both while stationary and when doing a drive test, no change.
I think I attached pictures of the battery up top. And I don’t have any monitors hooked up.
I think next option is to buy an obd11 and see what I can find.

Worst comes to worse pull it apart again and spend the big dollars on a new alternator.

SB50 is certainly a very popular connector here. I’ve had multiples of the in my beast.

And yes REDARC make sensational products. It is my long term goal to install their battery management systems. But I may have to win lotto first.

 

[Dellmassive]

Sounds like the alternator not operating.

Could be brushes,? regulator? Controller ?