Where to locate my D+ signal

[autorouter]

Thanks. I knew that box had the fuses for the fridge and step (took me ages to locate the step fuse when it failed). Didn't know it also had a D+ connection, but it now seems likely that I have a dumb alternator in which case I don't need to connect to D+.
Could be I've been seeking a solution to a problem that I don't have

It's worth sorting out a D+ trigger for the B2B (DC-DC charger) even if you have a dumb alternator. If you use voltage sensing instead, then anything that raises the starter battery voltage will turn on the B2B. Such as trickle-charging the starter battery, or charging the starter battery from solar. Voltage sensing is fine for simple systems, but can cause problems with more complex systems. D+ sensing just works.

 

[ForeignShaws]

Yes indeed. Looks like you need to find that D+ after all.

Found both the Fridge D+ and Towing D+ signal on the EM40 Interface just below the OS door pillar, below the Converters Interface PWB as described by HarryML7. I have no towbar so I'll use this for the charger.

 

[ForeignShaws]

It's worth sorting out a D+ trigger for the B2B (DC-DC charger) even if you have a dumb alternator. If you use voltage sensing instead, then anything that raises the starter battery voltage will turn on the B2B. Such as trickle-charging the starter battery, or charging the starter battery from solar. Voltage sensing is fine for simple systems, but can cause problems with more complex systems. D+ sensing just works.

Thanks autorouter, that makes sense.