Brake lights inop/hazards only work when turn signals on

[chop666per]

I have a 78 Brave 440. The taillights work as well as the turn signals but bulb does not light up when brakes are applied. I already replaced the brake switch and ran through all the wiring. The hazards come on when the knob is pulled and the blinker lever is in the left or right turn signal position. Possible turn signal switch?

[DaveVA78Chieftain]

12 volts DC is supplied to the Brake Light switch (front left wheel well just forward of master cylinder (hydroboost unit on M400/500/600 chassis)



from the 2nd fuse above the Hazard flasher:



The supply to the switch (F48-18PK; 18 guage pink wire) is routed through a red rectangular connector usually located on the floorboard at base of steeing wheel column.



The output of the switch (D9-18WH; 18 gauge white wire) is feed back to the hazard warning switch via a yellow rectangular connector (near the red one above) and white connector on steering column.



The white wire (D9-18WH) is connected to the H1 terminal on the hazard switch.


Given that the lights flash when hazard is selected, that means the everything past the hazard switch is good.
First check to see if you have voltage on the white wire at the steering wheel connector when brake is depressed.  If not trace back to the brake light switch.  If at steering wheel connector, then hazard switch is defective.

Dave