17' Series J35 Auxiliary supply no power

[Dazzler]

Howdy
I have a 2017 outback expanda. There is an auxiliary supply input to the J35 battery management system. I’ve swapped out the old J35 type B for a J35 type D with 103 control node which is all working fine (ie I can see the battery output and charge from solar and 240v). What provides the power to this auxiliary point? I have put a multimeter on the positive and negative and it shows no power when my van is connected to the my cruiser. The anderson plug is showing 12+ volts from my car auxiliary.
Darren

 

[Drover]

The AUX point is 12v Input usually from the tug........ The anderson on your tug is possibly for the fridge or maybe ESC if fitted.... If you have reasonable solar a charge from the tug isn't needed in most cases......................... The BMPro will select the what it thinks is the best supply.

 

[Dazzler]

The AUX point is 12v Input usually from the tug........ The anderson on your tug is possibly for the fridge or maybe ESC if fitted.... If you have reasonable solar a charge from the tug isn't needed in most cases......................... The BMPro will select the what it thinks is the best supply.

Thanks Drover
The Anderson plug supply on my tug is from a 55ah auxiliary. The original J35B already had an auxiliary input connected and have just swapped it over to the J35D. I believe the J35 will only allow the auxiliary charge if the aux input is 0.5v higher than the battery. My issue is that I’m not showing any voltage at the input, which is odd as it’s the original aux cable supply. Do you know if there’s a fuse or connection box for this supply as I can’t find it

 

[Drover]

If you have no 12v from the wire at the J35 then I would be starting at the tugs 12 pin for the power and work towards the J35 tracking the circuit, of course you may need the engine running to activate the circuit, really depends on how it was set up........ confirm you actually have an earth when you test that wire at the J35 before you start tracking though, many times a lot of hair pulling wasted if earths are checked out first.