Originally Posted by opus
Shouldnt there be relays involved? Can your idea handle them being all on at one time?
For the off road lights, there should definitely be relays involved. I've attached a picture of a wiring diagram that I drew up really quick. For the wire that goes from the accessory solenoid to your switch, and from the switch side ground of the relay, it can be a small gauge wire since it doesn't carry much amperage. The other wiring, from the accessory solenoid to the relay's load terminals, and out to the lights themselves, use something decent sized. Typically, the stock wires to the warning lights are around 14ga, but that is really a bit small. If it were me, I'd go with at least 12 or maybe even 10ga for max brightness. Wiring your lights up this way would make them able to turn on only when the engine is running or the key is in accessory position. If you want them to be able to come on without the key, then tap into the battery side of the accessory solenoid instead of the load side.
Edited to add that if you run new larger wires for the off road lights, you would probably want to put some kind of fuse inline between the accessory solenoid and the relay.
As far as using any of the warning lights for turn signals, I would advise against that if they are sealed beams. There are laws governing the amount of candlepower (CP) that a light facing rearward or a turn signal can put out - normally 32 CP, which is what bulbs such as 1156, and the high filament of 1157 put out. If you plan on using the sealed beam warning lights as turn signals, you are pretty much guaranteed a ticket.
My bus had warning lights just below the windshield that use the same 7-inch lens as the upper warning lights but used 1156 bulbs instead of sealed beams. If you could replace the sealed beam lights that you want to use as turn signals with these lower powered lights, I'm sure it would be perfectly legal. These are the lights you are looking for: Weldon.
Scroll down to the 1000-1010 Series if you want lights that use regular 1156 bulbs. If you want lights with black bases, you would want the 1010-1100-xx. Baader Brown
is also an OEM light manufacturer for buses.