Saga 2.0 gauge wiring help

[jz*supra]

I do not have a battery in my car, and i can't install one to find this wires myself. Sage gauges have 3 power wires, red b+, orange (on, the car power line that will not be disconnected at start of engine), yellow acc.
The yellow acc is obviously easy.
The red b+ is a constant 12V wire right?

My question is were do i locate a wire to connect the orange wire to? Will i find 1 in the wiring harness for my deck?

Thanks in advance.