Chris,

This is a response to your question from Bobby Hughes, EE, that has done the wiring on my 289 Unique Roadster. Bobby has done the wiring on all of my race cars for the past 15 years and I've never had a problem with anything he has done.


I suspect, since there's only one bulb per side in the rear, that the
brake lights are on the bright filament in those bulbs just like the
turn signal. If I splice the wire from the brake switch into the turn
signal wires the brake lights will cancel out the turn signal, and I
won't signal as long as the brake lights are on.
correct

From what I understand, many turn signal switches have a provision
for this, whereby when the turn signal switch is activated, it breaks
the circuit to the brake light, only providing current from the
flasher to the tail light, to ground.
correct again. The Unique one does not have this.

So I'm wondering if there's a provision in the turn signal switch
shipped with the kit that opens the brake light circuit when the turn
signal is activated, breaking the brake light circuit so that the
turn signal will flash when the brakes are applied.

If the turn signal switch doesn't have that provision, is there
another way of achieving this?
Terry's car came with an adapter wired in which is sold at trailering places to adapt a car with separate brake and turn signals to a trailer with combined brake and turn lights. Apparently the turn signal connections from the switch are connected to the turn signal inputs, the brake switch is connected to the brake light inputs, and the left and right outlets are then connected to the bright filaments of the bulbs. The adapter is the magic answer, unfortunately we just put the dash back in this afternoon and it is hidden so we can't see a name or part number. But any auto supply or trailering supply place should know what you want.

--
Robert W. Hughes (Bob)
Hopefully this will be of some help to you!

Regards,