Purple wires

[Hammotj]

Missing brake switch/pigtail for my 74. Found two cut purple wires that lead to the tailgate. Could those be for brake lights? Troubleshooting inop brake lights leading down this rabbit hole.

 

[Broncobowsher]

Do the rear turn signals work?

 

[DirtDonk]

Not unless someone went way off the rails for your wiring.
Is the wiring still stock, or is it a new replacement harness?

And when you say "brake switch" you are referring to the one up at the top of the brake pedal inside the cab. Correct? And not the one out on the distribution block for the Brake Warning lamp on the dash?

For the Bronco's stock harness, the wires for the brake light switch for the rear lights would be Red w/black strips I believe. One goes to the headlight switch (where it gets it's power) and the other goes up into the steering column to the turn-signal switch. Where it's then distributed to each rear lamp through the same wires as the turn signals.

Are these wires truly a dark Purple/Violet color? Or are they more of a purplish-pinkish color? That latter would be consistent with the brake warning lamp on the dash I think.
But the wires going out to the rear lamps are the color for the turn signals since they share the same bulb filament as the brake lights.

So non-working brake lights can be anywhere from the headlight switch, to the brake light switch, to the turn signal switch, to the rear lamps and all the wiring in-between.
More often than not though, I'd say that if it's not the bulbs or the sockets, it's the turn signal switch.
Do the turn signals work on the back?

You can test the brake switch on the pedal with a test lamp or volt-meter.

Paul

 

[Hammotj]

Do the rear turn signals work?

Yes.

 

[Hammotj]

Trying to add pictures (stand by for those). When we bought the bronco, the switch was present on the brake pedal but there were no wires attached to it. I found one red wire with black stripe near that area that had been snipped and was just hanging (and seems to be coming from the ignition switch…can’t tell for sure). And found two purple wires forward of the firewall under the driver’s side that were hanging free as well that can be traced to the rear lights that go to a four plug that turns into a five plug. I’m thinking one is for reverse lights and one is for the brake lights.

The reverse lights are not working. Tail lights (when heads lights are on) work and front and rear blinkers work as well.

We checked all the lights prior to purchasing it and they worked, but we had the dealer change the drum brakes out for power brakes, and subsequently did not recheck the lights. So I have a feeling they might have forgot to reconnect some wires.

 

[ba123]

I haven’t looked at Bronco wiring in decades, I’ll be there soon, but the purpose of that brake switch is to make your rear brake lights work. So I’d bet it’s a wire that goes to your brake lights, could be power but could be ground. The switch makes the connection and closes the circuit.

***of course I could be totally wrong, just my understanding.

 

[Brush Hog]

For reverse lights. There is a plug that goes into transmission then wires run to the lights. If I remember correctly mine were kind of a purple color. The plug was hard to find I had to buy a used one.

 

[DirtDonk]

Manual transmission or automatic?

 

[Broncobowsher]

Yes.

That proofs out the wiring and bulbs between the turn signal switch and the light themselves. That is NOT the problem. Don't go splicing in wires, you will just make more issues.

Your issue is 100% up front. The brake light switch feed goes to the turn signal switch. The turn signal switch not only does turn signals, but brake lights as well. More specific, when you go for turn, it disconnects the brake feed to that light and connects to blinking power. The disconnect is important so the light will actually blink and not just stay on. This is why you cannot bypass the turn signal switch and just feed the bulbs directly.

 

[Brush Hog]

Mine is manual. Plug looked like this. The black wire was dirty and looked a little purple too.

 

[Hammotj]

Manual transmission or automatic?

Automatic

 

[Hammotj]

Trying to add pictures (stand by for those). When we bought the bronco, the switch was present on the brake pedal but there were no wires attached to it. I found one red wire with black stripe near that area that had been snipped and was just hanging (and seems to be coming from the ignition switch…can’t tell for sure). And found two purple wires forward of the firewall under the driver’s side that were hanging free as well that can be traced to the rear lights that go to a four plug that turns into a five plug. I’m thinking one is for reverse lights and one is for the brake lights.

The reverse lights are not working. Tail lights (when heads lights are on) work and front and rear blinkers work as well.

We checked all the lights prior to purchasing it and they worked, but we had the dealer change the drum brakes out for power brakes, and subsequently did not recheck the lights. So I have a feeling they might have forgot to reconnect some wires.

Trying to add pictures (stand by for those). When we bought the bronco, the switch was present on the brake pedal but there were no wires attached to it. I found one red wire with black stripe near that area that had been snipped and was just hanging (and seems to be coming from the ignition switch…can’t tell for sure). And found two purple wires forward of the firewall under the driver’s side that were hanging free as well that can be traced to the rear lights that go to a four plug that turns into a five plug. I’m thinking one is for reverse lights and one is for the brake lights.

The reverse lights are not working. Tail lights (when heads lights are on) work and front and rear blinkers work as well.

We checked all the lights prior to purchasing it and they worked, but we had the dealer change the drum brakes out for power brakes, and subsequently did not recheck the lights. So I have a feeling they might have forgot to reconnect some wires.

 

[Hammotj]

 

[tirewater]

Trying to add pictures (stand by for those). When we bought the bronco, the switch was present on the brake pedal but there were no wires attached to it. I found one red wire with black stripe near that area that had been snipped and was just hanging (and seems to be coming from the ignition switch…can’t tell for sure). And found two purple wires forward of the firewall under the driver’s side that were hanging free as well that can be traced to the rear lights that go to a four plug that turns into a five plug. I’m thinking one is for reverse lights and one is for the brake lights.

The reverse lights are not working. Tail lights (when heads lights are on) work and front and rear blinkers work as well.

We checked all the lights prior to purchasing it and they worked, but we had the dealer change the drum brakes out for power brakes, and subsequently did not recheck the lights. So I have a feeling they might have forgot to reconnect some wires.

As DirtDonk mentioned, stock there were two purple wires from the fire wall to the brake differential/warning switch on the proportioning vale. The two purple wires are part of the rear wiring harness as it goes down from the fender to the frame, and then they split off to the proportioning valve. When they split off, they have cloth insulation and are ~20" in length.

Look at your proportioning valve, it's attached to the frame below the master cylinder, and the brake lines attack to it. It should have a connector on the top of it for a two conductor plug - similar to what Brush Hogg posted.

Do you have picture of your proportioning valve?

 

[Oldtimer]

Brake warning light gets power from key ON (R-Y)
Purple wires go to brake warning switch on porportioning valve, and provide ground for lamp.


Stop lamp switch needs battery power from headlamp switch (R), always on.
When activated, sends 12v to turn signal switch (R-BK). Can you find a R-BK wire coming from connector at steering column under dash?


Thanks to https://seabiscuit68.tripod.com/images/73-74_combined_v1.gif for schematics.

 

[DirtDonk]

I’ll have to say that even if you had unwrapped them from a very well protected spot, those purple/pink wires do not look like Ford original harness wires.
They look like they were added later and look new enough to be non-original.
Are they completely out of the harness as you follow them along? Or did you unwrap them?

But do it was suggested first, and see if they go down to the brake line distribution block on the frame.

Oh, and with an automatic transmission, your backup lamp switch is on the side of the transmission where the shift lever is.
The switch often wears out. It might just need adjustment, but more often than not. It needs replacing.