ls1nova71

iTrader: (4)

Glad you got it going! Where did you have your 3rd brake light hooked up to? It shouldn't affect anything as long as it's hooked up directly to the side of the brake light switch that is hot when the brakes are applied.

slosteve

I looked at our scribbled out 'diagram' and couldn't see where we connected it so I will find it tomorrow. I'd like it to work.

Steve

supershift67

iTrader: (1)

good deal.

BigEd_72455

iTrader: (7)

Try installing a relay to control the third brake light, that way it gets its actual power source from someplace else besides the brake circuit directly. That should isolate the LED from the cruise also, reducing the chance of interference. The relay will be activated by the brake output 12v positive, ground it to its mounting point (if metal), and run positive and LED brake power accordingly. I always go to a battery source (12V constant) for relay power.

Diagram below

ls1nova71

iTrader: (4)

If you can post up the schematic (take a picture of it if you have to) I can tell you where to hook the 3rd brake light.. The LEDs won't adversely affect the cruise at all, the reason I asked if you had LED taillights is because they don't have enough resistance for the PCM to see its ground through them. But just tapping off the side of the brake light switch that is hot with the brakes applied will work.

slosteve

Essentially that is what we did, but check this out. I connected the 3rd brake light again and it caused my brake lights to come on without the brake pedal being applied. I started looking around and found the wires for the LED were being pinched in the door jamb of the rear delivery door. The LED light is on that door. So, needless to say, I'm redoing that segment. The problem seems to be that the door opens a full 90 degrees so the wires don't always return into the opening I had made for them. Duh!
And thanks BigEd for the relay info.

Steve

Poncho72

iTrader: (1)

having cruise control is a must for me so #1 "tag" this thread. i am a bit confused (happens all the time) about the relation to LED tail/brake lights and cruise control. can someone clarify? i'll reserve more questions for later since my 05 DBW LQ4 engine and accessories are in route to me now so i'm just getting into the game. i have plans to use LED's wherever possible to minimize load, and cuz i like them. i.e. headlights, tail-lights, interior lighting, etc... hence the question.