: *How-To* Wire up Switchback LED's for Clear Foglights/DRL's

01-24-12, 05:27 PM
And they said it couldn't be done...

Finally got them to work!


I swapped to the eBay clear fogs on my base CTS a while back and was very happy with the look but did not like the orange daytime running lights shining all the time.
I sold the CTS and bought a V and finally got around to swapping over the clear fogs into it.
I came across the switchback LED bulbs but read that they would not work with the V's wiring. I bought the bulbs anyway and started figuring out how they would work with our cars.
It took about three hours for the whole install which included: jacking up the car, removing the wheels and fender liners, plastic skid plate, installing the clear fogs and running the wires for the new bulbs.
I went a little overboard as far as making all of my wiring connections at the light using some sort of quick-disconnects so they can be quickly removed without cutting the wires if I ever need to remove my bumper again.
It would take probably an hour and a half to two hours having the how-to and not worrying about all the quick disconnects at the fog light...

Tools needed:
wire strippers
soldering iron
heat shrink tubing/electrical tape
zip ties
20 ft or so of 18g wire
20 ft of 1/4" black wire loom
x2 1 amp diodes
x2 inline fuse holders
x2 1 amp fuses
razor knife
old metal coat hanger (for running wires through the grommet)
Spare female harness connector with at least 3 inches left on the pigtails.
(Harness needed to steal pins from. I got mine from the front signal bulbs of an Hummer H2)

The bulbs I bought:
http://img194.imageshack.us/img194/4692/bulbs.jpg (http://imageshack.us/photo/my-images/194/bulbs.jpg/)

The V only has two available wires at the turn signal. Those two are a ground and a combined DRL/signal wire. That combined wire provides a steady 12v output to keep the bulb lit for the DRL's and then pulses the same wire to provide the flash needed for the signal.
The wire colors referenced at the bulbs may be different in your car. The harness that I have pictured is the harness that came on the "eBay special" clear fog lights. This is where the multimeter comes in handy so you can test to make sure you are using the proper wires.
This is the two wire connector that came with my fog lights.
This seems backwards but the brown wire on my harness was the 12v wire for the TS/DRL's and the red wire was the ground wire.
The stock V harness has two white wires at this connector.

The switchback bulbs need three wires to function properly. A ground, a steady 12 volt DRL wire and a pulsed 12v wire for the signal portion of the bulb.
What I did in the photo below was carefully de-pin the brown wire and move it to the center position of the connector. This takes the V's TS/DRL wire and lights the clear LED's.

To de-pin it you just pry up the "pin guard" in the center of the female harness. This exposes the "lock" that keeps the pins from backing out. Gently pull the lock away from the pin and pull the wire free. Remove the silicone seal in the empty slot then move the brown wire over a spot and push it into place.
Take the new pin that you removed from the spare harness (mine happened to be blue) and insert it into the vacant spot on the right that the brown wire just came from.

Your harness should now look something like this:

The amber circuit in the switchback takes priority and shuts off the clear LED's any time there is 12v's applied to the amber input. This allows the existing DRL/signal wire to provide the power to the clear LED's and also pulses 12v's to it when using the signal. The pulsing 12v's is negated by the fact that you are now providing a new pulsed 12v signal to the amber input wire which triggers the amber LED's and overrides the clear output.

I started by jacking up just the front of the V. Removing both front wheels, both inner fender well liners and the plastic skid plate that protects the bottom of the engine. Then on to the wiring....

First, I needed to find another 12v signal wire in the vehicle that pulses with the signal properly.
The two wires I found using Directed Electronics wiring database (for 12v+ L & R turn signals) are located just inside the door on the left side of the dash. Remove the side cover and you will see a black connector with a tan locking latch over it. It contains roughly 30 or so wires in it.



The needed wires are:
Driver Side: Light Blue/White
Passenger Side: Dark Blue/White
They are in the corners of the connector. The light blue/white is a single wire and the dark blue/white has two wires going to one pin. You can use either of the two dark blue/whites since they share the same pin.
I tested the wires and the were the proper signal wires.
Next, disconnect the negative terminal on the battery.
I carefully pulled the harness loose from the underdash and released the latch so that I could extend the harness and work on it. Remove most of the tape from the wires to gain access.


You do not have to do this step but I did not want any issues if there was a problem with the added lighting system or the bulb so I ran a 1 amp diode inline (with the stripe facing away from the connector towards the new bulb) and an inline fuse holder with a 1 amp fuse to protect the circuit in the vehicle.
Better safe than sorry!


I soldered then taped up the two fuse holders/diodes in place and left them hanging (w/o fuses installed) while I ran the new wires out under the hood.
I just used two 16g black wires and labeled the ends L & R to avoid confusion. I found that the easiest place to run the wires was through the existing grommet that has the hood release cable running through it.
I slid my razor knife through it to open it up a little bit.
I then taped my two black wires to a coat hanger and pushed it through the grommet and found it out under the hood. Pull the coat hanger and slack from the wires.


Now you need to connect the black wires to the corresponding L & R fuse holder. I soldered everything together then neatly taped it back up.

http://img688.imageshack.us/img688/5813/loomedwiresran.jpg (http://imageshack.us/photo/my-images/688/loomedwiresran.jpg/)

http://img190.imageshack.us/img190/5813/loomedwires.jpg (http://imageshack.us/photo/my-images/190/loomedwires.jpg/)

You now have needed wires out under the hood and ready to run to the lights.
I ran the new wires and loomed them then zip-tiepd them to the hood release cable starting behind the coolant resevoir and all the way down to the drivers light. Once my connections were made on the drivers side I then ran the passenger wire under the vehicle and zipped tied it to the existing wire harness that were already ran across.

http://img706.imageshack.us/img706/6039/enginebayi.jpg (http://imageshack.us/photo/my-images/706/enginebayi.jpg/)

http://img46.imageshack.us/img46/9647/underside.jpg (http://imageshack.us/photo/my-images/46/underside.jpg/)

To avoid the "hyper flash" I had to use a 50 watt 6 Ohm load resistors. When wiring these in, wire them between the ground wire and the factory DRL/Signal wire that is now in the center pin of the three pin harness. This will keep the V happy with the flash pattern.
Make sure to mount them solid to a metal part of the car. They get hot at times.

http://img16.imageshack.us/img16/944/loadresistor.jpg (http://imageshack.us/photo/my-images/16/loadresistor.jpg/)

Things learned:
The bulb color is listed as "xenon white". I contacted the company and asked them what light output color that was closest to and they told me 6k but they do not match the factory HID color at all. They have a slight bluish tint to them.
This bugs me a little but they two bulbs are never on at the same time because the clear LED's are for Daytime Running Lights and turn off automatically when the headlights come on.

These projector type bulbs are super bright which is awesome. You can easily see 10-15 feet in front of you in a dark area at night just off of these bulbs.
But, they only provide directional light forward so there is very minimal light actually reflecting off of the chrome reflector in the fog light housing so you can tell where the light is coming from instead of an overall uniform output.
I wouldn't mind see someone use the tower type switchbacks to see if they look any different just for curiosity purposes...


01-24-12, 07:16 PM
I like this mod man and curious to see your photos!

01-24-12, 07:53 PM
Thats pretty bad ass. I was told about these by another member here, (Kingoftypos). I was a bit skeptical, but now, after you doing such a great job, ill get them. Thanks for the wright up bro.

01-29-12, 01:38 PM
well done.. looks clean, thanks for sharing

01-29-12, 04:39 PM
Excellent job on the DIY, cant wait til it warms up a bit and make some time to do this...

03-23-12, 04:05 PM
sx54dx great write up and video man! I did this swap on my V. How are the switchback LED's from ijdmtoy holding up for you? One of mine started a constant blink on the DT running light (white) after 15-20 min of use! The controler inside the bulb was over heating or something.... worst part when i went through all the trouble to take it back out, the heatsink had separtated from the plastic bulb socket part!! :/ I was pretty pissed about that. They have already had to replace a backup bulb due to very low output out of the package and didn't send me my whole order the first time (which i just discovered). I like the products they offer but damn, i must be the only one having horrible luck with them. They appear to be doing a good job of rectifying the problems so far though I'll give them that.

03-26-12, 10:32 AM
Thanks for the compliment! Glad to see it was useful.
The switchbacks are holding up well so far. I have not noticed any issues out of them.
They do get warm though!
However, I used some 1157 projector style bulbs they offer for my reverse lights and one of them was very dim out of the package.
When I went to pull it out to check it, I accidentally pulled the heatsink off of the housing which separated the bulb.
That's when I realized that there was a resistor inline on one of the wires inside the housing and not on the other side.
I removed the resistor then superglued the housing back together and it has been working fine since at full brightness.
Glad they helped take care of it for you. If anyone finds a better source for bulbs let us know!

07-31-12, 10:06 PM
I just ordered 5000k towers from V-LED. This looks like a great, doable fun mod. Thanks for figuring it out. Good write up and pics.

08-01-12, 09:02 AM
Ya no kidding....killer write up! I'll have to do this at some point. Thanks!

07-24-13, 11:07 PM
Thanks a lot for this write up. I've had my eBay clear fogs installed for a month or so now, and have wasted all kinds of money on finding bulbs that I liked; all to no avail. So, I'm taking the dive on a set of THESE (http://www.ebay.com/itm/Dual-Color-Switchback-3157-3457-LED-Turn-Signal-Lights-Resistors-F7-/190748080995?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c6978bb63) and will be following your write-up to get 'em working right.

One question I have is regarding tapping into the appropriate fuses. How'd you do this, exactly? Also, is the entire job of getting into that side panel/harness optional? Or did you tap into those wires, then head down to the fuse panel? Sorry, I'm a complete NOOB with electrical.

08-08-13, 04:02 PM
Good one! Worthy project......although one (minor) detail: Don't solder your connections....you are much better off due to vibration to use a crimp connection. Cut the crimp end from eye connectors to do a short compact wire splice or to insert components like the diodes. Soldered wires are stiff and will fracture and are a serious avoidance in aircraft wiring for this reason - and a 'V' has a kind-of airborne sensation now and then! Yep, sure does!

But this is a project that has been added to this to-do list!

Thanks with 'mucho' kindness!!!


08-08-13, 05:38 PM
Thanks a lot for this write up. I've had my eBay clear fogs installed for a month or so now, and have wasted all kinds of money on finding bulbs that I liked; all to no avail. So, I'm taking the dive on a set of THESE (http://www.ebay.com/itm/Dual-Color-Switchback-3157-3457-LED-Turn-Signal-Lights-Resistors-F7-/190748080995?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c6978bb63) and will be following your write-up to get 'em working right.

One question I have is regarding tapping into the appropriate fuses. How'd you do this, exactly? Also, is the entire job of getting into that side panel/harness optional? Or did you tap into those wires, then head down to the fuse panel? Sorry, I'm a complete NOOB with electrical.


08-09-13, 05:17 AM
Crimp, don't solder....

03-08-14, 06:23 PM
Looking to do this soon since I'll have bumper off for headlights. One question though. Couldn't you just piggyback off of the signal wire already at fog lamp for your third wire and not have to run all the extra wire? I may be reading the required function for the switchback to function incorrectly though. What do u guys think?

03-09-14, 10:05 AM
No. If you piggybacked off of the signal wire at the bulb, your amber LED will run when the DRLs are on. You wouldn't have any white. The switchback works by making the amber LED the priority. OP stated that in the first post. So, any time the amber LED gets current to it, the switchback turns off the white LED and turns on the amber. If you piggy back at the bulb, the signal wire will be getting current while the DRL is on, thereby giving the amber LED current. The switchback would then give the amber LED priority and you would have an amber light constantly on.

You would have a similar problem with the side markers because those are turned on when the headlights are on, so you would have your amber LEDs running anytime the headlights are running. You need a wire that has current through it ONLY when the signal is flashing.

03-10-14, 03:23 PM
I don't recall seeing this mod before. I like it!

03-24-14, 05:03 PM
This is exactly what I've been looking for :)

06-27-14, 04:20 PM
can the op repost the photos that can not be seen?

08-29-14, 05:03 PM
Just did this mod last weekend and I love it. Thank you for the great write-up. It was very easy to complete and looks great without the amber DRLs. The only problem I see is that since the DRLs are always on during the day, the resistors connected to them that prevents the hyperflash get EXTREMELY HOT from that constant power!! (I have a brand on my arm to prove it. I accidently bumped into one after it was on for a few minutes) Although I did attach them to metal, it is still a concern of mine. Thanks again.

09-20-14, 05:24 PM
Does anyone know if the same procedure needs to be done on a 2009 STS?

02-20-16, 01:32 PM
I was able to complete this yesterday. We were able to piggyback off the side marker lights for the flash signal, and everything works great.

02-24-16, 07:52 PM
I was thinking you could get the extra wiring from the side turn signal. What did you use to tap into it?

Also, with the resistor getting so hit from the DRL, could it be put in the path of the turn signal wire? This would be the source of the hyper flash and would lessen the heat caused from always on operation.

02-25-16, 07:19 PM
I just used one of the safety splices, then taped it all up. I fastened the resistor to the flat metal piece of the inner fender skirt, so it should be all good.