Need help with wiring!

[98SVTtour]

So I used to have underglow and the only tube left functioning is the back one. What I wanted to do is make the rear tube illuminate when I press on the brakes.

I currently have that light connected to a switch and it works just fine when I turn it on; but I'm not quite sure how to wire it to the brake lights.

I was thinking I could just run the positive wire from the switch to the positive wire on the brakes but am not quite sure which is the positive. There is an orange, blue, and black wire. Also, after reading all the problems people have with their brake lights I became weary and wanted to make sure I do this right so I don't mess anything up.

Any help would be greatly appreciated. Thanks in advance for the help guys!

 

[98SVTtour]

I thought this might help as well.

Here's how I have it currently wired...

http://www.streetglow.com/site/Media/Manuals/an100.pdf

 

[98SVTtour]

Anybody have anything for me?

Even if anyone knows which of the wires for the brakes lights is the positive wire would help a ton.

 

[Matt R]

Does the tube require a transformer or anything? Or does it just run off of 12v? If so, just get a quick splice connector and attach it off the brake light positive wire. Run the ground/black wire of the tube to metal on the car or to the other brake light wire with another quick splice connector.

Otherwise you'll have to run the wire from the switch to the back of the car, and hook it up to a relay.

 

[98SVTtour]

Yeah the tube runs to a distribution block.

Any clue on which of the brake light wires is positive. If I recall last I looked there was an orange, blue and black.

Also, I'm not very wire savvy so how would I connect it to a relay?

 

[Matt R]

More than likely the orange wire is positive. Get a circuit tester to confirm.

A 4 prong relay would have one prong hooked up to a ground, one to 12v, one to the 12v switched (whatever comes on and you want that to control the tube), and one to the tube.

 

[Chas]

Ok, so if you have the Blue line series neon, they have their own transformer on each tube, so the only thing you'll need is the tube it's self. You can get rid of the distribution block. What you need to do is connect the Black w/White stripe wire on the tube to the brake light wire*, and the black wire on the tube to a metal surface with a self tapping screw and ring terminal:


*Matt R is probably right. The brake light is probably the orange wire, blue is the turn signal, black is the ground. To find out you'll need to remove the driver side tail light (I picked this one as this is the side the wiring harness runs along) and unplug the light from the connector:

Take a multimeter and set it to V= 20 (or test probe):

Touch the black lead (or clamp lead) to bare metal - cleaning of a bolt head with a wire brush is usually the easiest. Touch the red lead (or test probe) to the orange wire terminal on the brake light connector, and have someone step on the brake. If you have the right wire you should see approx 12V, if not try the blue wire. Once you have the right wire, follow that wire approx 16" back along the wiring harness, to somewhere just along the trunk floor. Next we'll need to tap into this wire. The best method is to solder, but for ease of use, we will use a 3M T-tap:

Do not use a side-by-side tap (they are not as reliable):

Use a pair of pliers to snap the T-tap onto the brake light wire. Next you'll attach the Black w/White stripe wire from the tube to this T-tap using a spade connector and crimp tool:

Then plug this wire into the T-tap. If everything went correctly, the neon tube should illuminate when you step on the brakes!

Good luck!