Generator wiring

[John Churchill]

I just purchased a 1980 FC33 and it's a bit of a project. The
original genset has been removed. A prior owner started to install a
Onan Marquis Gold 7kW unit. The 120V wiring is hooked up, but all the
12V stuff is just a mess. Nothing labeled, loose wirenuts, etc. No
starting battery has been installed yet. I have just put in a ground
for the genset and pos/neg battery cables.

My unidentified wires are:
1) 2 reds joined with a wire nut in one loom
2) 2 greens just loose with exposed ends in another loom
3) one orange with a small ring terminal and a much longer purple (or
maybe brown) with a broken off terminal in their own loom
4) one big black battery cable that does not have continuity to ground
or voltage from either the charger or the battery bank

Things I know are disconnected are the microswitch for the door lock
indicator, the oil pressure and temp gauges (and the hour meter but I
thought that worked off one of the other leads.) There does not seem
be be a hot wire for battery charging present.

Air slide cylinder is absent and the hose is just kinked off.

Anyone able to identify which wires go where? An original wiring
diagram or picture of the factory installation would be helpful.

John Churchill
Sanibel, FL