V1 Third (3rd) Brake Light

[Robinjo]

The videos mention the Third brake light to keep for cruise and I've read the diode trick.
What if you actually want to run a third brake light? Do I just wire it in and ground it out to the frame? Will cruise control still work in this situation?

Note: the double spelling in the title is just for future searchers that spell it each way. 3rd

 

[Gtstorey]

It depends on what type of 3rd brake light you use. If it’s the same type of bulb as the cobalt used it should work. If led then a resistor is needed.

 

[k.rollin]

My donor didn't have cruise and I have never used it in my cars that do. My CHMSL is an LED unit from a Chevy Colorado, so I run three wires to it; the light blue CHMSL wire, a wire that I spliced into the reverse lights, and a ground spliced into the grounds from the tail lights. No resistor. If you're retaining cruise control, I think LED CHMSLs require a resistor.

 

[Robinjo]

It depends on what type of 3rd brake light you use. If it’s the same type of bulb as the cobalt used it should work. If led then a resistor is needed.

If you run a LED type, what type of resistor is needed?
Can ground just go to the frame or does it have to link into the system somehow?

 

[Gtstorey]

I will say I've had limited luck with the cruise. It may be something in my tune but it will disengage when it tries to accelerate up hills. This is a somewhat common problem on the LNF, so others may not be affected. I don't use cruise on vehicles that much anyway so really haven't tried to trouble shoot it.

 

[Gtstorey]

Cruise control | DF Kit Car Forum

If you run a LED type, what type of resistor is needed?
Can ground just go to the frame or does it have to link into the system somehow?

 

[k.rollin]

Can ground just go to the frame or does it have to link into the system somehow?

I'm pretty sure that they all run back to the chassis, regardless of whether you splice it into another ground wire or you add a ring terminal and run a self tapper into one of the tubes

 

[Rauq]

Amazon link

Run from the positive lead to the third brake light to ground. That link has 5 load resistors which will also take care of your hyper flash if you have all LED turn signals as well. I have one on my CHMSL but haven't gotten to the turn signals yet, so I still have hyper flash. Some folks have said the resistor isn't at all necessary for cruise to work, but I never did try running it without- I was chasing missing cruise control and I installed the resistor before I found the separate and unrelated issue.

 

[baustin]

As an 06 SC/SC you likely don't need a resistor for cruise to work... That's only specific models that require it and your model isnt one of them.
I had an 06 SS/SC donor, with a LED 3rd brake light and cruise works perfectly and I never added a resistor. No reason to overcomplicate things.

The only resistors you might want are for turn signals to not flash too fast if running led on rear and/or front. I don't have any but am ok with the fast flashing, its not quite too fast for me.

For the 3rd light you have to use the specific wire for the 3rd brake signal and ground the light to the frame somewhere nearby, I think I did by the fuse box.

 

[Rttoys]

Yep. 06 it’s not needed. I don’t have a 3rd brake light and cruise works fine.

 

[Robinjo]

Yep. 06 it’s not needed. I don’t have a 3rd brake light and cruise works fine.

So I can run any type 3rd brake light I want, if so desired?

 

[Rttoys]

I don’t see why not. I will be adding one someday and it’ll be an led of some sort. Like baustin said, there is a specific 3rd brake light wire for it, too.

 

[Robinjo]

I did save the specific 3rd brake light wire.