Thanks Phil and Scalf77. I think the "start" wire is connected wrong at the ignition since it is always on, not just during start. I just got the van used, but saw where two owners ago they said to keep it plugged into shore power when possible. I'm in a condo where that is impractical, but I get plenty of solar. I think the start assist drained the engine batteries completely. Right about the ground and active monitoring. The unit is way underpowered to keep the 12v refrigerator running 24x7, so my main concern is not house batteries, but engine power for starting.
Can anyone point me to a diagram of the ignition connector? I'd like to get the start wire in the right place whether or not I replace the separator.
BTW, thanks Scalf77 for the battery-isolators-separators-switches-and-more-updated-2020 post. Very helpful.