Tail light trouble.

[Pittsburghkid]

So to start i have an 84. I wanted a thrid brake light so I got an 86-87 tail light harness and third brake light assembly and hooked them up. First the original harness didn't have the second pigtail with the single light brown wire hooked up (why I don't know) so when i put the new harness in I connected that pigtail. So i hit the brakes and all the necessary lights light up except the third brake light. I tried another bulb and the same result. Now the pigtail from the tail light harness has a light blue and black wire on either end and a brown wire in the middle however the harness for the third brake light assembly only has the black and light blue wire one either end and not the brown wire in the middle. So my question is, is the third brake light not working because of the missing wire in the middle and if so why is it there on one harness and not the other? And why would the part of the harness with the single light brown wire not be hooked up previously. BTW the taillights and marker lights also aren't working (brake lights work) even after checking all fuses but that's a problem for another day but if you have an answer for that also I'm willing to listen. Thanks

 

[GullsGN]

See this thread. It looks like you need a switch on the pedal.http://www.turbobuick.com/forums/general-turbo-buick-tech/334018-3rd-brake-light.html

 

[Pittsburghkid]

why is nothing ever easy with these cars? any idea what the single light brown wire is for on the harness? I wonder if it would be easier to just splice the third brake light in than adding the switch for it.

 

[turbobooster]

hey man im in the middle of hooking up a 3rd brake light in my 85 as well just waiting on the light but the wiring on the light should b just the black(ground) and light blue (power source) from my understanding and what i have seen what does ur gang connector plug in the trunk look like? in the picture below is a pic of what mine looks like and if u see in that big plug towards the right of it theres a blue wire that connects to nothing im going to plug into that and see how that works out i havent tested it yet but will do later today or tomorrow for sure does ur plug look like this ? and by the way ive seen 3rd brake lights that came factory and i havent seen any brwn wire or anything except for the 2 black and light blue hope this helps

 

[turbobooster]

the blue wire im talking about hooking up my 3rd brake light to is the top blue wire in the pic

 

[Pittsburghkid]

here's what i have going on. The pigtail from the tail light harness has a third brown wire in the middle yet the third brake light harness only has two wires in the pigtail. (black & light blue) The light brown wire on the end that matches up with a light blue wire wasn't connected when i took my old harness out so I'd like to know what that wire goes to and whats the best way to wire in this third brake light without having to go the the extremes.

 

[turbobooster]

yea not sure what the middle brown wire is for or why its there and i dont have that other connector on the end that wasnt plugged in but is now in ur pic

 

[49-blues]

I just tied into the white wire off the brake switch on the steering column for hot to the light & a black wire to ground,done several this way never a problem and works like it should.

 

[turbobooster]

do u have a pic of this white wire u tied into ?

 

[49-blues]

It comes right off the brake switch under the dash on the steering column.

 

[turbobooster]

how did u guys mount the bracket in the back for the 3rd brake light ? looks like i might have to drill some holes but i dont see how the bracket would go can u guys maybe take a qwik pic of how u mounted it thanx