How to install DDM HID kit on low beams w/ relay harness

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vt_hokie2008

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2007 Tahoe LT, putting in DDM Tuning 35W 6000k HID kit with relay harness.

First off, I've installed 10+ of these kits with the relay harness and have found a few issues with the harness. The primary issue is the fuse holder does not seal from the weather, so it corrodes over time and you get misfires and eventually the lights will not turn on at all. To fix this, I removed this:
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and replaced it with this, which I purchased at Advance Auto and then soldered into place. Note: this fuse holder does not come with a fuse, so you will need a 30 amp bus fuse to put in there.
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Remove the airbox
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On the passenger side, behind the headlight housing you will see a black rubbery sheet, get the top of it loose (two clips) and you will have access to the low beam bulb easily.
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The drive side is similar, however the windshield washer fluid reservoir is in the way. I removed just one clip on that side and worked in a tight space.
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On both sides I removed the top two screws that hold the headlight housing in. This allowed the housing to move a little and made it easier to work with.
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As for wiring the harness, the red and black wired plug connects to the ballast, the other plug connects to the factory bulb plug, as seen here:
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I got my power here:
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And my ground here (this is under the airbox)
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The bulb wires up to the ballast in only one way, there is an extra plug running through the grommet that you will not use.
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I zip tied the ballast to this metal bar behind each of the headlight housings, then stuffed all of the ballast wires behind the black rubbery sheet.
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I ran all wire harness wires under the plastic pieces above and in front of the radiator and zip tied where necessary to keep things tidy. Here are a couple of pictures of the lights on.

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Any questions, just ask.
 

VTburban

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A big thanks to Alex on this; this was done at my request...great job, thanks again.
 

Freedom Motorsports

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OUTSTANDING write up indeed! Nice work Alex! Also, nice upgrades to the kit to solve issues, and thanks for telling everyone about them!
 
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vt_hokie2008

vt_hokie2008

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OUTSTANDING write up indeed! Nice work Alex! Also, nice upgrades to the kit to solve issues, and thanks for telling everyone about them!

Thanks! I've gotten tired of troubleshooting these things over and over only to find the fuse is corroded.
 

crazycrew

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So is the relay a must. I have a set of hi, lows and gigs waiting for me to install. Can I make this relay myself if I absolutely need it or do I have to order from ddm?
 
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vt_hokie2008

vt_hokie2008

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So is the relay a must. I have a set of hi, lows and gigs waiting for me to install. Can I make this relay myself if I absolutely need it or do I have to order from ddm?

I'm not sure as to whether you NEED the relay harness or not. The easy way to tell is to hook up to the factory wiring and see if they turn on.

You can make the harness yourself, but it's $15 with the order from them or $25 without ordering a kit I think, so up to you if it's worth it (though I'm sure making it yourself would lead to a cleaner install since wires would be the length you need an no more etc plus better components).

All the harness does is hook up to the factory wiring, when your lights are switched to on, the relay gets triggered and sends 12V to the ballasts for them to fire the bulbs, pretty simple.
 

crazycrew

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I already have the hid's so making them would be more feasible. But, I'm an electrical dummy????????
 
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vt_hokie2008

vt_hokie2008

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I already have the hid's so making them would be more feasible. But, I'm an electrical dummy????????

I'd try them out without the relay harness first and see if they function. I think I've seen on here where people don't have the relay harness and they work just fine. If they don't, I can put together a diagram of what you would need to make in order to get it going.
 

crazycrew

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Thanks. I'll probably need the diagram. I'll let you know how it goes. Won't have time for the install until next week though
 

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