find wiring information on the B-1 here: http://www.inpowerdirect.com/docs/TB-34A.pdf
Terminal 5 is grounded to negative for power to operate the controller, flasher, and relays.
When the [warning] master switch is turned on, +12 volts is applied to Pin 4, arming the system.
As a driver approaches a stop, he presses the "start" button momentarily applying +12 volts to Terminal 6
This causes power to alternately go out through Terminal 7 [right] and Terminal 8 [left] to flash the warning ambers.
When the bus stops, the driver opens the door, and the door switch grounds Terminal 3.
a.) the amber flashers stop
b.) power to the red lamps alternately comes out Terminal 9 [right] and Terminal 10 [left]
c.) power to activate the stop arm solenoid comes out Terminal 1
Turning on the double-pole "override" switch both applies a ground to the door switch terminal, and applies +12 volts to the override terminal.
I speculate that removing the ground from the door switch (closing the door) shuts down the red lights and stop arms, and that the override switch shuts them down with the door still open. Maybe someone who has driven a route can confirm that.
So, if you are looking to re-use the overhead lights,
the four heavy wires next to the four 20-amp fuses feed the bulbs through the rusted terminal connections in Photo 2 -
. Wire power to re-use the lights to here through fused fog light relays (or perform surgery inside the B-1 to divorce the relays installed on the unit from the flasher circuitry, and re-use the fused relay portion of the assembly). The two small wires probably go to flash the amber and red indicators on your switch panel to advise the driver the warning lights are on.
Photo 3 -
This is a group of self-resetting circuit breakers for critical systems that can't tolerate a blown fuse while operating. The cylinder at the bottom of the photo is a solenoid. It is probably either an ignition or accessory solenoid, but it could be the one between the flasher and stop arms, or perform some other function. One of the small wires on the small stud in front goes to the key or control switch, and applies power to activate the solenoid when it is "on." This connects the two big studs together applying power from the batteries to the switched circuits.
I can't see if the heavy wire at the bottom of the circuit breaker assembly comes from this solenoid or someplace else. The heavy wire at the bottom is the hot, inside there is a metal bar up the middle connected to this as a hot distribution buss, and the wires on the right and left come out of the individual breakers to the protected circuits.
Photo 4 -
The orange blocks appear to be disconnects to pass various wires through a chassis wall like it would pass through a firewall. The added fuses are mechanics' aftermarket work. They are either band-aids to keep troubled circuits going, or were added to power accessories that were not installed when the bus left the factory.
I hope this helps.