On my 1978 280Z,The brake lightsare on separate BULBS than the turn signals. I spent a week or two cleaning and replacing the bulb sockets, and replacing bulbs. Even the wiring diagrams in the Hayne's and Mitchel's book agree with me.

Maybe the car you are referring to is different.

I was refering to the 240Z's and the turn switch that comes on just about all of them.

the brake light wire goes through the switch in question

I think you are right about tail lamps that use the same bulb for brake and turn tignal. I was referring to a 280Z that uses separate bulbs for both.