LED Headlight, Turn Signal & Brake Wiring

OptimizePrime

Well-Known Member
Full disclosure: this is not my realm of expertise, I'm effectively handicapped when it comes to understanding some of this stuff but I could use your help!

I'm not using the standard headlights, sideview mirrors, or rear lights and this creates a 'fun' opportunity for me. While searching, information is spread between threads waiting to be found like the needle in a haystack. For those who are planning to go down this route, my goal is to consolidate the headlight, sideview mirror, and rear brake light wiring here. For those of you who have done it, any advice is much appreciated.

I have a 2010 Cobalt SS TC

HEADLIGHTS

FunctionHarness Wire Color
High BeamWhite
Low BeamYellow
Park LightBrown
GroundBlack

I have your basic two wire (ground - black, power - red) headlights. I have them wired as follows: Black = Black, Yellow = Red. I do not have a high beam or parking lights.

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TURN SIGNALS / SIDEVIEW MIRRORS

FunctionHarness Wire Color
GroundOrange
Turn SignalGreen
Park LightRed

I have your basic two wire (ground - black, power - red) turn signals. I have them wired as follows: Orange = Black, Green = Red. I do not have parking lights on my turns.

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REAR LIGHTS
DRIVER SIDE / PASSENGER

FunctionHarness Wire Color
Turn Signal & BrakeYellow / Dark Green
Park LightBrown
ReverseLight Green
GroundBlack

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I have four wires coming from my tails -- since the cobalt used the Yellow wire for Turn Signal & Brake how do I wire the Red & Yellow LED light wires to it? How do I go about figuring out the size resistor? halp

LED FunctionLED Wire Color
GroundBlack
Park LightWhite
BrakeRed
Turn SignalYellow
 
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Ross

Well-Known Member
I didn't add a resisitor to the rear LED tail lights, just hooked them up to 12V.
So take your rear LED lights over to your 12V battery, and put the black on ground, then put the other wires on positive, one at a time.
You need to find which wire is the reverse white light, and which wire is the bright red light.
You seem to be missing a wire for the reverse lights.
You also have the yellow wire as Turn Signal, and red wire as Brake, but those are both the bright red, and should be one wire.

Also note that the Cobalt wiring has a rear left turn/brake wire, a rear right turn/brake wire, a front left turn wire, and a front right turn wire.
 
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Tony

Well-Known Member
As Ross said, the turn signal and brake light at the rear are the same "bulb" so to speak - the BCM will control it so that it will flash appropriately whether your brakes are on or not. The rears are shown in the middle of the picture. The unlabeled "B" terminal is the tail light (dim red). On the left is the front turn signals - a completely different circuit. The "B" terminal on those would be a running light, which you obviously won't need to worry about. As far as resistors, the only one I think needs added is on the center stop lamp in order to make cruise control work. I'm not familiar with that, as I haven't done it yet - I only just got my cruise switches wired up, so I haven't tested to see if it works or not yet. The rest don't need resistors - I haven't gotten any bulb out warnings, and the BCM controls the flash, so no "hyperflash" issues.
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I have a good amount of wiring info in my build thread if you feel like sorting through it, as I also didn't get the kit headlights, taillights, or turn signals, so we're a similar boat on that. I just have been going a little nuts on the headlights, so front end stuff is fresh in my mind.
 

OptimizePrime

Well-Known Member
Thanks guys! Ross you're correct I'm currently missing an integrated reverse light - I'm going to add that separately.

I was speaking with Lonny about something unrelated and brought this up - he had a moment of brilliance and mentioned I should tie into the sideview mirrors for the rear turn signals and the CHMSL (third brake light) for the brakes, parking lights and reverse would come from the normal rear harness wires. This would effectively bypass the yellow (driver side) and green (passenger side) brake / turn signal wire.

I tried a Silvania 6ohm 'load balancer' / resistor from autozone on the chmsl that was not plugged into a light and couldn't get the brakes to turn on. I wired this with one end of the resistor to the CHMSL (light blue wire) and one end to the drivers side ground. I don't think the 6ohm resistor is bringing the voltage low enough based on the link below, and will return it and try an 8ohm resistor in the same fashion. Do I have to have a light plugged in? With a light plugged into the chmsl, I would assume a 6ohm resistor would work.


(more chmsl info: https://dfkitcar.com/forum/index.php?threads/chmsl-wiring.714/#post-11389 )
 
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Lonny

Administrator
Staff member
If your running different brake lights from the ones we supply that separate the turn and brake lights you will need to tie into your front turn signal light wires. They are green wires that attach to the mirrors.

For the brakes you will need to split the light blue CHMSL wire and run one to each brake light.

If you plan on using cruise control you may need to install a resistor to ground. The LED lights by themselves may not pull enough of a load to activate the cruise control.


20200212_113141.jpg


Load resistor
Load resistor.jpg
 

Tony

Well-Known Member
Sorry, I misunderstood that the actual lights you're using do have separate circuits for turn and brake. In that case, what Lonny illustrated would work, or you could just not use the turn circuit and wire the brake circuit as factory. I don't know what the actual light itself looks like, so I don't know if that would look weird, but it would save the extra complexity I'd think.
 

OptimizePrime

Well-Known Member
Thanks for the help guys, the problem I'm facing with the CHMSL is that it's a constant 7.5v without the brakes pressed which is enough to turn the LEDs on (so they're on all the time).

Edit: Looks like without the actual 3rd Brake light to draw the voltage <1v and turn out the LEDs, it'll sit at 7.5v. So, if one wants to keep their third brake light, an Impala light works best and then you can run lines to your brakes. If don't want a third brake light and you want to run your brakes off of the CHMSL you must wire in a 100ohm resistor.

The resistor is only for enabling cruise control and not impacting the brake lights.

 
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