How to Install 3rd Brake Light In a 84 Grand National.

[87grandnational]

How do I do this little thing. I got a 3rd Brake Light out of a 87 Regal Limited.

It works, I tested it. I have it mounted perfectaly, I just need to figure out how to get it hooked up to the right wires.

Which wires. Or shoot me a picture on how it should work. Cause I am about to have a heart attack if i dont get this done.

Can someone please help me?

Thanks,
Cody M

 

[84TXGN]

Since the brake lights also work as blinkers, I think the only way to do it right is to run it to the brake switch under the dash. I could be wrong and hopefully someone who has done this will chime in.

 

[87grandnational]

Tried that, whenever the brake pedal is not depressed, the light is on. when you press down the brake pedal, the light goes off.

 

[Turbo1dr]

You'll have to get a brake light switch for the 86-87 model. I believe there's a separate wire on the switch just for that.

 

[salvageV6]

You will need to run a wire up front to the brake switch on the pedal assy.

Ground the light on some metal in the trunk or back seat area.

The white wire off the brake switch (87 cars anyway), is what you are looking for, goes to +12 volts when you hit the brakes.

It shouldn't hurt to add the one lights worth of current draw to the existing brake switch it's not a huge bulb anyway.

You must get the wire off the brake switch before it gets into the turn/hazard switch assembly which I believe is the same on the 84's.

If not you will need to post or find the wiring diagram for the 84 cars.

 

[83ttypecooled]

Hi,
I think you hooked up to the cruise control brake switch, Try the other one.

 

[CTX-SLPR]

Why couldn't he just wire into the brake signal wire at the rear of the car with either a direct pull and ground the bulb or with a relay that triggers whenever the brakelights are depressed. I'll state now that I don't and never have had a G-body but that is how my classic Buicks were wired as I remember.

 

[Jerryl]

You will need to run a wire up front to the brake switch on the pedal assy.

Ground the light on some metal in the trunk or back seat area.

The white wire off the brake switch (87 cars anyway), is what you are looking for, goes to +12 volts when you hit the brakes.

It shouldn't hurt to add the one lights worth of current draw to the existing brake switch it's not a huge bulb anyway.

You must get the wire off the brake switch before it gets into the turn/hazard switch assembly which I believe is the same on the 84's.

If not you will need to post or find the wiring diagram for the 84 cars.

Right on the money. Same color wire. Just completed this last week.

 

[84TXGN]

Why couldn't he just wire into the brake signal wire at the rear of the car with either a direct pull and ground the bulb or with a relay that triggers whenever the brakelights are depressed. I'll state now that I don't and never have had a G-body but that is how my classic Buicks were wired as I remember.

The brake lights are also the turn signals so which ever one you wired it into would cause the 3rd brake light to blink whenver that blinker was used.

 

[John Larkin]

The factory setup uses a wire all the way to the brake switch. I think it's light blue. Any other color will cause an instant explosion. :biggrin:

 

[Blazer406]

Tried that, whenever the brake pedal is not depressed, the light is on. when you press down the brake pedal, the light goes off.

You could wire up your own double position relay to that..... just a few dollars... and when your current switch went off.... your relay would switch on......

 

[jimmy1063aa]

How do I do this little thing. I got a 3rd Brake Light out of a 87 Regal Limited.

It works, I tested it. I have it mounted perfectaly, I just need to figure out how to get it hooked up to the right wires.

Which wires. Or shoot me a picture on how it should work. Cause I am about to have a heart attack if i dont get this done.

Can someone please help me?

Thanks,
Cody M[/QUOTE
...

 

[jimmy1063aa]

...

 

[garyk1970]

You will need to run a wire up front to the brake switch on the pedal assy.

Ground the light on some metal in the trunk or back seat area.

The white wire off the brake switch (87 cars anyway), is what you are looking for, goes to +12 volts when you hit the brakes.

It shouldn't hurt to add the one lights worth of current draw to the existing brake switch it's not a huge bulb anyway.

You must get the wire off the brake switch before it gets into the turn/hazard switch assembly which I believe is the same on the 84's.

If not you will need to post or find the wiring diagram for the 84 cars.

this correct.......make sure theres not a unused light blue wire in the bulkhead connector near lh taillights under carpet in trunk....if not run wire like stated by salvagev6 and run wire to brake pedal switch connecting to white wire.

 

[Jerryl]

this correct.......make sure theres not a unused light blue wire in the bulkhead connector near lh taillights under carpet in trunk.....

I am contunuesly amazed by your E-xpertise.
Now I "HAVE TO" go look.

 

[garyk1970]

I am contunuesly amazed by your E-xpertise.
Now I "HAVE TO" go look.

Ive seen some very late 85 models that had the light blue at the rear bulkhead,but very few. all the 86(when law came in to have the third light) and 87 and up have the light and the light blue wire ran....if you want to update your car,the running of the wire is most likely needed.
for further searchers,if the wire (at the pedal)has power at pedal rest,you're looking at the cruise/tc lock up switch.....you want the white wire off the upper switch (the brake switch).the cruise/lu switch has the large cruise servo release vacuum line.

 

[turbobooster]

Just did mine few weeks ago if u need pics of the wire and how I spliced into it lmk it's really easy

 

[dartguy340]

The factory setup uses a wire all the way to the brake switch. I think it's light blue. Any other color will cause an instant explosion. :biggrin:

Ditto...BOOM!