Brake light switch question

[MikeyM73]

Hi all,

If it's not one thing, it's another. Apparently, my brake lights are no longer working. There were, now they're not. I previously had removed the fuse box and run wiring from there to the rear for the CHT guage and I must have pulled something loose but I can't find what. The bulbs are good and I tested for power at both brake light switches (key on and off) but have no power at any of the 3 tabs in either of the 2 brake light switch connectors. I do have the Bently but the 73 wiring diagram is a little confusing. Does anyone know where the wires that feed power to the brake light switches on the master cylinder come from? I believe it should be fuse connection 12 (far right side), according to the owners manual and I have power there with the key on.

I'll keep chasing it but wanted to see if anyone had any ideas.

Thanks,
Mikey
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'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[Clementine79]

Not sure dealing with the same here, let me know if you figure it out.

[busdaddy]

You are correct, fuse #12 powers them, a black wire that joins a thin harness (3-4 wires) that leads down into the nos ahead of the steering column connects it to the switches. The key has to be on for testing.
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[MikeyM73]

Thanks BD. So the black/yellow wire and a black wire are joined into one connection.. that goes down through the nose/body, the black yellow goes onto the horn and the black continues on to the switches, correct? if so, I tested continuity from that joining terminal where both wires meet and between the black wire on the switch recepticle side.. no continunity. Looks like maybe a broken wire.
_________________
'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[MikeyM73]

Well, looks like there was a break along the 5 or so ft path. Ran a new wire and I have brakes.
_________________
'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[busdaddy]

Good job!
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[MikeyM73]

Why thank you. So... odd thing... When I replaced the black wire the turn signals stopped working. So I touched the old black wire I cut to a hot lead and got turn signals back. So I reconnected it to its original spot and I’m good there. But the manual showed that black wire to run only to the brake switches and nothing else unless I read it wrong. So it looks like it fed the turn signals and brake switches but the break or “no continuity “ was somewhere along the path to the switches but I sure didn’t see where it fed the turn signals.
_________________
'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[Clementine79]

The wire you had a short on, where does it run underneath? Is it enclosed in a tube that runs to the rear brake lights?

[MikeyM73]

On my '73, the wire I was dealing was factory crimped with another (black/yellow to the horn) and went from the top of fuse position 12 into a small harness and came out at the brake light switch(es) on the master cylinder. You can see the small harness as it comes out from the cab, under the nose belly pan on the inside of the passenger side frame rail. According to the manual, that wire should have only gone to the switches but I think mine was spliced in somewhere with the turn signals because they stopped working when I cut the original black wire. So I reterminated it and reconnected it and got turn signals back but have a new fresh wire for the brake light switches.
_________________
'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.