1970 Road Runner - Brake Lights not working

[Norv]

My 70 RR brake lights are not working. I have checked the bulbs, brake switch on brake pedal, and fuses. I understand that the wiring my also route through the steering column at the turn signal switch. Why the heck would they route brake light wiring through the turn signal switch/steering column?

Also, the car had been idling rough when headlights are on and/or using turn signal. The other day the car shut off when I activated the parking lights (weird). I turned the switch off and it cranked right back up fine. Maybe there's a short somewhere? I also checked the ignition coil. It seems to have the proper primary and secondary ohms.
I have also installed a new voltage regulator, ballast resistor, and starter relay switch recently.

The electrical diagrams look very confusing to me so I'm hoping someone has some simple suggestions on what/how to check for the problem (brake lights out and sluggish idle with lights on). Thanks in advance.

 

[R413]

You have a bad TS switch.

Why are the brake lamps through the turn signal switch? It is so the front turn signals don’t light up when you step on the brake pedal.

 

[RemCharger]

If the brake switch went directly to the brake bulb, how could it flash when you used the turn signal.

Right, it would have to go through the turn signal switch.

 

[Norv]

You have a bad TS switch.

Why are the brake lamps through the turn signal switch? It is so the front turn signals don’t light up when you step on the brake pedal.

The turn signals are separate bulbs aren't they?

 

[Norv]

If the brake switch went directly to the brake bulb, how could it flash when you used the turn signal.

Right, it would have to go through the turn signal switch.

The turn signals are separate bulbs aren't they?

 

[RemCharger]

The turn signals are separate bulbs aren't they?

No sir.
That idea wasn't common until the 80s ish

 

[Norv]

1157 bulb has 2 filaments.
Dim one for running lights
Bright one for brake and turn signals. they illuminate the same filament

So, what's the second bulb on each side for, the flashers?

 

[WileE]

Check your grounds.

 

[RemCharger]

So, what's the second bulb on each side for, the flashers?

No. All brake, turn, and 4ways work on the same filament. Tail light ( park lamps) work the dim filament.

 

[Norv]

A 70 Plymouth b-body has 2 bulbs in each lamp. The bulbs on each side of the car both do the same thing.

a 1966-69 Plymouth b-body has one build in each taillight.

go look at your sockets and wires, the wires are the same color on both sockets on each side.

And what is it that the two bulbs on the '70 do?