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Backlight wiring for Diode Dynamics fog lights

Applies to All Model Years 
10K views 12 replies 5 participants last post by  MadeOfCoffee 
#1 · (Edited)
Hey all, I have a question about wiring up my new DD SS3 fog lights. I chose the backlit option and I'm trying to decide where I should wire them to. There were no recommendations in the install instructions for wiring. My first thought was to splice them into the low beams. I have them on most of the time and I imagine I want my sweet fogs backlit most of the time too. DD sent some wire splicers with the harness. I guess I could always use a relay from the battery and just splice in the switch wire, but I'm pretty sure the harness has an in-line fuse. Is there a typical way to wire these? It doesn't seem worth it to make a dash switch just for fog backlights.

Also I'm sorry if this question has already been asked; I did a bunch of searching and came up empty.

Edit: I found DD instructions for the SS3 pods that just say "tap a 12v switched source" and list the backlight draw as 30mA, so I suppose it's pretty safe to just splice into the headlamps.
 
#2 ·
Update: I just received a reply from DD about what I should do:

"Thanks for reaching out! In this particular case, I wouldn't tap the low beam, as your foglights (the main beam on the SS3s in this case) only turn on when your headlights are on anyway. Additionally, anywhere in the engine bay should be just fine, as the Crosstrek does a great job of limiting exposure in the engine bay. If you were worried, you could simply apply a little dielectric grease and wrap the connection in electrical tape (though the tape should be enough).

Finally, the DRL wires should be light blue on all trims (apart from the hybrid) and the sidemarker wires should be a traditional blue. I would probably recommend the DRL wires myself, as the parking lights will generally come on with your low beams (when you would probably want to run your foglight main beam)."

I'm not sure my 2019 premium has DRLs but maybe there's parking lights? Will investigate.
 
#4 ·
I haven't had the weather or the time quite yet to rip everything apart and get familiar with the wiring. I'm also not very familiar with my 2019's exact conditions for each light to be on or off...I don't even know for sure if I actually have DRLs. Maybe its the side marker bulbs, or maybe its the high beams with lower voltage? I've been trying to do internet research but it's not helpful as there are so many trims and model years now. I think I'll actually have some time tomorrow. I'm guessing I'll most likely use the wires DD recommended. I'll get on this as soon as I can and get back to you.
 
#9 ·
Just replaced the Baja Designs with the DD SS3 Pros (backlit) today, using the side markers with the wire taps.
Works fine, but I wouldn’t mind pulling from the DRLs for the backlights, if anyone has figured out yet where those wires are.
Frankly, I’m just happy to have some fogs in that fit, and don’t require me hacking up the fog light surrounds.
I’m also impressed with the wiring harness quality on the Diode Dynamics units over the Baja Deaigns: proper Deutsch connectors vs no-name janky crap haha!
 
#12 · (Edited)
Woo I finally did it! The box only sat for 7 months. Sorry all. The worst part was wrestling with the pop clips under the fog lamps themselves, ugh.

Ok so all I did for wiring the backlights was snip off the connector that they so nicely crimped on the end for us, and used a t tap to connect into the drl wire. The wire is almost exactly as the diagram DD sent me shows. There is a big gray plug with many colorful wires running to it directly below each headlamp assembly, about middle of each. For me, the R/passenger side one had something like 2 black and white wires, an orange, maybe a pink or something, but also a light blue. The L/driver side is similar but has 2 brown and white wires (instead of black and white) along with the other colors. It also has the blue. The blue wire is the drl wire that I t-tapped the fog's backlight wire to on each side. Worked perfectly for me. I just had to (carefully) cut open the tape over the wires off the plug to give myself a little more space to tap.

Also, I used regular t-taps because I didn't really like the ones DD sent with the lamps. I don't think it matters.

It got dark as I finished, but I can try to take photos tomorrow. Here's the diagram DD send me again for reference. I can't speak to what color the wires are on newer treks but I would hope they kept the same scheme.

Rectangle Font Line Slope Parallel


EDIT: Upon rewatching the video I took to check if I was successful, I am thinking that the backlights came on with the side markers and not just the drls. I may have actually failed. I will investigate further.
 
#13 ·
Woo I finally did it! The box only sat for 7 months. Sorry all. The worst part was wrestling with the pop clips under the fog lamps themselves, ugh.

Ok so all I did for wiring the backlights was snip off the connector that they so nicely crimped on the end for us, and used a t tap to connect into the drl wire. The wire is almost exactly as the diagram DD sent me shows. There is a big gray plug with many colorful wires running to it directly below each headlamp assembly, about middle of each. For me, the R/passenger side one had something like 2 black and white wires, an orange, maybe a pink or something, but also a light blue. The L/driver side is similar but has 2 brown and white wires (instead of black and white) along with the other colors. It also has the blue. The blue wire is the drl wire that I t-tapped the fog's backlight wire to on each side. Worked perfectly for me. I just had to (carefully) cut open the tape over the wires off the plug to give myself a little more space to tap.

Also, I used regular t-taps because I didn't really like the ones DD sent with the lamps. I don't think it matters.

It got dark as I finished, but I can try to take photos tomorrow. Here's the diagram DD send me again for reference. I can't speak to what color the wires are on newer treks but I would hope they kept the same scheme.

EDIT: Upon rewatching the video I took to check if I was successful, I am thinking that the backlights came on with the side markers and not just the drls. I may have actually failed. I will investigate further.
I think the best approach is to tap to the fuse box (just need to find the right fuse so amber light will be on with ignition on), the thing with tapping to DRL harness is if the model doesn't come with LED DRL (like premium models, where high beams are also DRL), then amber light is gonna flicker. Same thing happens when you try to replace high beam halogen bulbs with LED. If the wiring on one side (passenger side) is too short to reach the fuse box you can tap it to the driver wiring then > connect to the fuse box. I've been too lazy to touch them so let me know if you choose that route :D.
 
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