I need someone who is really sound in their F-body wiring. Here is my problem:

Installed TA tail lights in my 1990 Firebird... wiring harness came out of a 87 or so TA. Problem was that there is no unplug w/ 90 Firebirds... so I did a hack job making the center two brake/tail lights and the outer set blink. Well, it doesn't look good. I decided to do this... all 6 brake/taillight, 3 on each side blink. Okay, well, no problem, right? Wrong.... here is the problem. It seems w/ Trans Ams the brake lights are run through the blinker system or something, somehow. There are 4 wires back there... Dark Green (left turn), Yellow (Right Turn), Light green (back up) and brown (Tail lights). In the 90 there is an extra... blue... that means one thing... that is the brake light. Darn... bad thing... so right now I have it hooked up w/ 2 diodes running to each set of turn signals, and a Y connection off of the Blue Wire (brake light wire). It means I do have blinkers... but as soon as the brakes and blinkers are applied (happens a lot if you think about it) the blinkers don't work at all. I think all the lights on the side that is supposed to be blinking turn off! ARG!!! Anyway, if anyone would be willing to help me fix this problem I would be much much appreciated!!!
Thanks,
Douglas

 

If you don't have two separate filaments to use for the turn / brake light functions, than use a relay to control the single filament & perform both functions. Connect the brake light power in to the pole contact. Connect the NC contact to the single filament. Connect one side of the relay coil to the turn signal wire. Ground the other side of the relay coil. This will make the 4 way flashers inoperable, and the current sensing turn signal flasher will have to be replaced with a non-current sensing type flasher.

Tim

 

I forgot to include a second relay on each side - I'll post a schematic on Monday, showing the connections for the 4 relays (two relays for each side) to control a two bulb brake / turn system from a 4 bulb brake / turn harness. The 4 way flashers will work with this configuration, but you will still need to replace the factory current sensing flasher, which will not flash if a bulb is burned out, with a non-current sensing type flasher, like is used in the 4 way flasher circuit.

Tim

[This message has been edited by Tim Burgess (edited March 10, 2001).]

 

Thanks a ton, Tim!! I am looking forward to having working brakes and blinkers at the same time :-)

 

You should just hook it up the way the factory did. Run a short length of wire between the brake light switch up to the one wire on the steering column (in a flat inline plug) it at the end. I'll make up a pic.



Notice how termial 17 isn't used? Tie brake power into this. Then your blinkers are your brake lights and will flash correctly! Use brake power (blue wire) for 3rd brake light only.



[This message has been edited by JoelOl75 (edited March 11, 2001).]

 

From the factory there was no brake light wire... at least for the tail lights that I got.... but I am interested to see.

 

You can get power right off the switch on the brake peddle. It's only a 6" run to the steering column wire. If you do not have a center brake light this is all you will have to tie together.

I'm pretty sure GM ran it even in apps w/o seperate turn signals even before 86 (center brake light). Anyway you say the harness cam from later than this so it has to be there for the 3rd light. it runs to the contact plate near the hatch mechanism to power it.



[This message has been edited by JoelOl75 (edited March 11, 2001).]

 

Hey, that's a great idea! I didn't know these turn signal switches could control a two filament signal / brake light system - cool!

Connect the white wire on the edge of the turn signal connector (position P, which does not go any where, at present) on the steering column to the light blue wire coming from the brake light switch. That makes the yellow & dark green rear turn signal circuits now dual function (brake / turn). At the rear of the car, connect the 3 bright filaments on the left side to the yellow wire, and connect the 3 bright filaments on the right side to the dark green wire. Also, connect all 6 dim filaments to the brown wire - running lights. The light blue wire will now be a no connect at the rear of the car.

Tim

 

Joel, you rule!! Thanks man, I am gonna try this out tomorrow.
You have any idea if I can just cut the blue wire and splice that into connection 17 because me third brake light is run off of a yellow wire w/ a black stripe. It didn't run into the blue wire anywhere I could see.
Thanks a ton!
Douglas

 

I did the mod to my '92 Z to try it out. The turn signal & brake light bulbs now both function as turn / brake indicators.

The blue wire is the one to connect to the white wire (#17).

Tim

 

Hey, it works!!! I am so so so so happy!!! Thanks a ton, guys! Though I need to remember to cut wires a little longer next time... there where some tight fits because of me messing up.
Thanks,
Douglas
P.S. for anyone else who tries that just cut the blue wire, atleast in a 90 Firebird when you are cutting the one that comes off of the brake pedal.

 

I wonder how it would look if you modded the amber lens somehow to make it red. Prob wouldn't look too much different.

I switched my formula (amber turns) to GTA lights and man.... I tried relays, trailer wiring boxes, NOTHING worked. I was getting steamed so I went to the junkyard and started poking around the back and noticed the blue wire was tied back in the harness, then up from that spliced into a blck/yellow for rhe 3rd light.

So I was thinking they added some kind of box in the front somewhere.... Didn't make much progress that day!

So I broke out some older wiring diagrams for the firebird (82) and compared the turn signal ckt's to a later camaro and that was the diff. Now I could crack myself in the head for wasting a spool of wire, messin with relays, and wasting about 35 hours and 35 bucks trying to figure this out.



------------------
'88 Camaro RS 2.8L
'88 Formula 350 (Too many mods to list...)

 

You know... a technical article might be worth it being how many people change from base model to TA tail lights.....

 

You can install red 1157 bulbs (from Jegs) behind amber lenses, and the lights will look red, at night. I did this on the rear of my '92 Z28.

Tim

 

Oh how I love this search engine!
Been messing with my taillight conversion today,and couldn't figure out why my brakelights didn't work.
I ran a search here,and this thread found my problem instantly.
I just simply ran a jumper from the brake switch to the white wire on the t/s switch conn. and WHALA! I now have brakelights!
thanks guys,even though this thread is old as hell,it was VERY helpful for me.