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

[vt_hokie2008]

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:

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.

Remove the airbox

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.

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.

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.

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:

I got my power here:

And my ground here (this is under the airbox)

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.

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.

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.

Any questions, just ask.

 

[VTburban]

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

 

[vt_hokie2008]

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

You're welcome, hope this helps you out

 

[Freedom Motorsports]

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

 

[vt_hokie2008]

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]

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?

 

[vt_hokie2008]

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]

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

 

[vt_hokie2008]

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]

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

 

[blkonblk]

great write up, i just installed mine and did the exact same thing. I did not use a relay for the low beams and they work just fine. I also installed HIDs on the fog lights and it looks great

 

[vt_hokie2008]

great write up, i just installed mine and did the exact same thing. I did not use a relay for the low beams and they work just fine. I also installed HIDs on the fog lights and it looks great

What HIDs did you put in the fogs?

 

[foxracingfreak]

Is it necessary to install a relay harness on the highs and fogs as well?

 

[vt_hokie2008]

Is it necessary to install a relay harness on the highs and fogs as well?

I haven't done those, but I would imagine so. Just like the low beams though, I've seen some people having success without using the harness and just plugging into the factory wiring.

 

[RollTide2]

I used your guide and everything works great except one thing. When I unlock the car sometimes only one like comes on. What did I do wrong?

 

[vt_hokie2008]

I used your guide and everything works great except one thing. When I unlock the car sometimes only one like comes on. What did I do wrong?

Typically this happens if you don't use the harness, but you may have a "special" set. You'll need to swap bulbs/ballasts from side to side to determine if you have a bad bulb or bad ballast. In other words:

take the ballast from the driver headlight and put it on the passenger side and the passenger side ballast on the driver side. If the driver side was the one that wasn't turning on, and now it's the passenger, then you have a bad ballast. If the driver side still doesn't turn on, you have a bad bulb.

Once you've done that, you can contact DDM. Their replacement policy kinda sucks, they want you to ship them the defective part, they'll test it, then send you a new one. Meanwhile, you don't have HIDs. Whenever I've had that problem I've either gone back to stock or just purchased another set of bulbs or another ballast since they're pretty cheap.

 

[RollTide2]

Alright I'll do this tommorow afternoon and let you know what happens.

 

[MC153]

Used the info about the fuse on my obs. Couldn't solder it worth the crap but I got new one in there. Thanks.

 

[vt_hokie2008]

Used the info about the fuse on my obs. Couldn't solder it worth the crap but I got new one in there. Thanks.

You're welcome, glad it helped.

 

[gbleezy]

I have a DDM kit and last night had to drive home with my high beams on because the HIDs weren't working. Pulled out the 20a fuse in the relay and the plastic part is all melted. Should I replace it with a 30a fuse? I'm a little concerned that the plastic was melting, what would be causing this?