Hef88

Okay, so let me start with year and model, 2004 Suburban...but this post applies to Tahoes Yukons/ XL and pretty much any Chevy with the daytime running lights that have the variable voltage, (which you all know either blows one bulb repeatedly or if you run LEDs they last a few months then start to die off one by one.)

After a few months of intense research on the web and talking to friends, I finally found a fix that allows me to run LEDs for the daytime running lights and for all turn parking and break lights without blowing bulbs and no backing feeding of voltage to other lights during use of one bulb.

First, the DRLs, what is needed is simple, a 12v 30A single pole single throw relay. find a common ground for the coil and use the blue wire (could be diff on your vehicle but its the + wire going to one of your DRL lights) going to the drivers side DRL light for the other side of the coil. then find a good 12v source to run through the contact and take the normally open side and split it into 2 and run to the DRL lights making sure the original + wire to the DRL is cut and now spliced to the relay. Now what you have is the variable voltage powering the relay when the daytime running lights are on and a good constant 12v (13.8 or so when running) powering the LED bulbs for the DRL lights. No more LEDs failing one at a time!!!!!!

Second, LEDs for front parking/turn and rear tail/brake and rear turn. At each turn signal bulb 2 front and 2 rear, you need to install a 6 ohm 50w load resistor in parallel to the bulb making sure you use the + wire for the turn circuit on the front lights and not the parking light + wire. In the rear turn there is only the + for turn and the ground so it should be obvious which to wires to use. What this fixes is any fast flashing because when you install LEDs your turn signals will fast flash because the LEDs don't put a load on the circuit so the circuit thinks there is a burned out bulb. Now in the front parking and rear parking lights you need to install in series a 3A 50v diode in the + wire with the silver band on the diode facing toward the bulb. Also on my vehicle I have 2 small marker lights up front I put a diode there as well. Now what this fixes is no parking lights flash when using a turn signal and the parking lights dont come on when using the brakes. The diodes stop any back feeding voltage through the parking light circuit and only allow voltage to go to the bulb.

I hope I have helped many of you out, it is very hard to find a solution on the web for this, but here it is, a little time consuming to make it all look right with solder and shrink tubing but the outcome is well worth it.

73shark

Great write-up!

Curious as to why the 12VDC would vary on the lighting ckts in the first place and not all ckts?