[Baratong]

...

I have a couple of mystery boxes that I was hoping someone could identify
and point me to the schematic that this was wired up with.

....

here are the two boxes

The first one looks like some type of a 2-wire data bus spliter. Could be CAN-BUS, but I would expect to see at least a ground wire as well. Possibly an RS485 2-wire setup.. If you could get a picture of the lettering on the chips that are visible on the board, it would go a long way to helping to identify the box's function.


On the second box, you would need to share a picture of what's inside the box including any chip labeling...

 

[Baratong]

Ha. The first one is a fuse holder, why.
The second one has a sets of leads that go to the passenger compartment/ back set of batteries- I'm still tracing many- and a set going to another box that is some type of distribution for the charger.

The 2nd picture shows what appears to be two voltage measurement circuits that both send serial data out the middle pair of wires.

Each of the 2 circuits use a PICAXE CPU, and an xPC817 opto-isolator. This would be the measurement and data sending section. Probably sending the data out to a display in the dash?

On the outer edges of the board (on either side) there is a power resistor, a wirewound trimmer resistor, and a fuse. This section would probably be a voltage divider to get the incoming voltage down to a range the CPU could work with to take the measurements.


Of course this is guesswork based on what would be most likely... I'm interested to see where each of the three wire pairs terminate.