3rd brake light ?

turbostang79 · Dec 21, 2003

I was all excited this weekend, my GT spoiler was finally finished and ready to mount !
The mounting part was pretty easy, and it looks great !

But how do I wire the 3rd brake light in the spoiler ?
I've been checking all the wires behind the dash, at the drivers feet, and at the rear lights, but there is no wire that ONLY powers the brake lights ? Every wire that powers when I hit the brake, also powers the turn signals. And visa versa, the turn signals seem to be connected to the brake wires ???
If I just attach the 3rd brake light to the normal brake lights, the 3rd brake light will act as a turn signal also.

Anybody has ever done this before ? I've been looking all day for a freakin wire, is it really that hard, or am I missing an important thing here ? (or am I just that stupid)

It's on a '79 hatchback btw.

mr_woodster · Dec 21, 2003

i have an 87 hatch, the 3rd brake light wire runs inside the hatch, down the driverside (still inside) the hatch and pop's out near the driverside hinge. Since mine was an lx, it had a the connector right there for the 3rd light already, yours may be differnt, but i wouldnt think so. Open your hatch up and see if there is a wire run upto there (take off the insde molding next to the rear driverside glass, closest to the hatch, look around, it may be there!) . Just throwing out some ideas, usualy ford wires stuff to a certain extent, even if that option wasnt available on that perticular model.

Mustang5L5 · Dec 21, 2003

well 3rd brakelights didn't come on Foxes til 1986...so he doesn't have the wiring

What he needs to do is run some wirung from the 3rd brakellight up the hatch and into the main body, then run the wiring down to 1 taillight

On the taillight there will be a dual-filament bulb and three wires to it. 1 is ground. 1 wire is the parking lights, and the other wire is the brake light. You just need to tap onto that wire

turbostang79 · Dec 21, 2003

Great ideas, keep'm coming

mr_woodster, no luck for me today. There wasn't any extra cable laying around.

If I wire it up like Mustang5L5 sais, the 3rd brake light will also blink with the turn signals, that's the problem. There are indeed 3 wires on 1 bulb, 1 ground, 1 parking light, and 1 for brake and turn signals.

I think I'll just tap a wire coming from the brake switch, attached to the pedal, and do my own wiring, with a relay. After searching for a whole day, it looks like the easyest way out.

Mustang5L5 · Dec 21, 2003

turbostang79 said:
If I wire it up like Mustang5L5 sais, the 3rd brake light will also blink with the turn signals, that's the problem. There are indeed 3 wires on 1 bulb, 1 ground, 1 parking light, and 1 for brake and turn signals.

Ah i forgot you had a '79 where the brake and turn signal is the same. I was thinking of the 83-later lights where they are seperate

How bout this...

Since the 3rd brake light has two sides and two seperate bulbs...why not wire the left blub to the left brake/turn signal and the right to the right turn signal. That way the 3rd brake light will also act as a turn signal.

Another step further would be to retrofit some 3-wire bulbs int he third brake light. You can wire 1 wire to the parking lamps and the other to the turn/brake.

just some ideas...i think it would be unique

GTPhreak · Dec 21, 2003

you will have to run a new wire all the way up to the brake switch on the pedal

turbostang79 · Dec 21, 2003

Mustang5L5 said:
Since the 3rd brake light has two sides and two seperate bulbs...why not wire the left blub to the left brake/turn signal and the right to the right turn signal. That way the 3rd brake light will also act as a turn signal.

Another step further would be to retrofit some 3-wire bulbs int he third brake light. You can wire 1 wire to the parking lamps and the other to the turn/brake.

that would indeed be a great mod !
and easyer than wiring it up the normal way
I don't think I'll be able to pass technical inspection next year with a blinking 3rd brake light

hmmm, I'll just install the relay coming from the brake switch when going to the inspection. The rest of the year I'll drive with the blinking 3rd brake light

HOWNDOG · Dec 22, 2003

See if you can find a auto parts store that still sells those high-mount brake light kits for older cars and copy the wiring diagram out of it? Maybe the after market spoiler manufactors can get you a diagram too?

HD

turbostang79 · Dec 22, 2003

HOWNDOG said:
See if you can find a auto parts store that still sells those high-mount brake light kits for older cars and copy the wiring diagram out of it? Maybe the after market spoiler manufactors can get you a diagram too?

HD

I went to a local shop today, and they agreed with GTPhreak, I'll have to run my own wiring. It should be pretty easy, just tap from the brake switch ( if it's a + cable )
If it's a ground wire I'll have to use a relay. No biggy, I should be able to do it.
That's for the 25th when I'll finally have a day off !

I'll be posting pics in Talk this week, the spoiler looks soooooo good

thank's for the input guys !

niizhmkwa · Dec 27, 2003

I have the same problem

would you please let me know what you do so i can connect my spoiler as well I have an 1982 coupe please help me Too thanks Twobears

turbostang79 · Dec 27, 2003

niizhmkwa said:
would you please let me know what you do so i can connect my spoiler as well I have an 1982 coupe please help me Too thanks Twobears

It was pretty easy.
On the brake pedal there is a switch with 2 wires.
One of them is constant positive. The other one obviously gives power when you hit the brakes.
I just tapped a wire from that one to the 3rd brake light, and it works like a charm
Just make sure you've got a good ground on your 3rd brake light.
Doesn't really matter wich wire you take at that point. There was a black one, so I took that one for the ground. (...)

Oh yeah, maybe this might help you, on the brake switch, the two wires...
The constant positive was green-red, the second one wich I tapped from was plain green ....
Just attach a test light or a simple multi-meter to it to make sure

Pulling the wires so you don't see them was the hardest part.
I had to remove almost all interior trim on the drivers side.

happy toolin' !

3rd brake light ?

turbostang79

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3rd brake light ?

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