I was curious how my thee position "emergency start" dash switch worked, so I checked it out today. What I found is that the merge switch is off when in the middle position. My merge solenoid has only one actuating positive wire going to it. Thus, moving the dash switch either up or down does the same thing which is to activate the solenoid. There is no switching to the house or chassis battery bank.
on ours when switched to Engine the Starting Batteries Energize it and when switched to House then the house Batteries Energize it.
Chester the way I thought it works is with the switch in one position then one solenoid is powered by one set of batteries then in the other position the other solenoid is powered by the other set of batteries.
Forest, I only have one solenoid, but Steve may be correct in that the up and down positions of the dash switch may be energized from either the house of chassis batteries. I will test this today and report back.
there is only one solenoid, but i would be surprised if it wasnt actuated by switching between house and engine batteries. that is the purpose of it
tom