No brake lights

[jess p]

Hello gang


I have no brake lights. Recently replaced the alternator, battery and voltage regulator so
I’m not sure if any of that plays into the equation. However I have replaced the following

Alternator
Battery
Voltage regulator
Flasher
Bulb for alternator warning light on dash.

Checked main power relay on relay board
Checked brake light switch
Checked brake light bulbs
Checked all fuses under dash.

Findings
No power to fuses.

This evening I’m just going to trace from the brake lights on back to the dash.
Now from looking at all wiring diagrams where does power come from?

My car is a 1970

Does power come from the fresh air relay on fuse board under dash or does it come
from the ignition switch. That is to the fuse that powers the brake lights.

Thanks in advance.

[Dave at Pelican Parts]

Check the wiring diagrams in your Haynes manual. (If you don't have one, get one. Inexpensive and has most of the info from the factory manuals.)

Going backwards from the brake light:
The brake light bulb is a dual-filament bulb, which is basically two lights in one glass housing. There are two metal spots at the bottom of the bulb instead of one; one is for each filament in the bulb.
The brake light filament is powered by a black/yellow wire. It gets its ground from a brown wire plugged into the taillight housing.
This wire goes through the main wiring harness to the brake light switch, which is on the pedal cluster. This switch either connects the wires going to it or disconnects them.
This wire gets its power from fuse #8, which powers a number of other things (with "switched power") in the car.
This in turn gets its power from the ignition switch, through a black wire.

If you have no power to the fuse panel at all, you've got a pretty fundamental problem. Start with the battery; make sure it is hooked up. It wouldn't be the first time a connection was left unconnected after replacing some parts. And it won't be the last.

Check all of the connections that you touched when doing the above work. Most especially if everything worked before you replaced the parts!

--DD

[jess p]

Thanks Dave

[John Rogers]

Might want to check the little brake light switch and is the arm on the right side of the metal disc so that when brake pedal is pressed the circuit is complete and the lights light up.

The switch and the round metal disc can be adjusted so lights come on when pedal is pushed but no pressure from the master cylinder. This is very, very handy if racing as the car(s) behind you will hit their brakes to keep from running into you.
John Rogers the oldracer