I need to add a note to this diagram that when everything is working correctly, the batteries appear to be connected in parallel, except when auto stopped. Trickle charging and jump starting should work from the main battery.Yeah, you posted right before my question.
Have you seen the wiring diagram?
If this is correct, it doesn’t appear your method will charge the aux unless the N1 and N2 are connected on the PCM.
N2 and N3 are connected to main battery, but then it’s up to the power control rely to be closed in order to charge the aux. Maybe this is the case.
Pic is from the thread. Not mine.