hid relay harness ... should i even bother?

[slocar]

I ordered it with my HIDs from DDM and it was on back order, and just came in ... I bought it in case I have problems with firing and what not, but I've been running them with the ballasts drawing straight off the factory wiring with no issues for 3 weeks now.

I know it's safer with the harness, but I don't know if the effort of making a clean install (I'm a neat freak when it comes to stuff like this) is worth it.

What say you?

[russiankid]

Its worth it in a sense that it relieves the load on your electrical system. I just did a relay setup on low beams and fog lights, and my voltage stays rock steady at 14.1 on idle vs before it would drop to 13.7 when the HID's fired up.

[coffee328]

You may be w/o issues now, but the ballasts' toll on your stock wires is a slow-moving process...and I prefer to all-out avoid a bad situation. When I was test firing my retro w/o the relay wired in, my gauges would dip...which was a sign that the ballasts' start-up period was pulling more voltage than the e36 wires were designed for. The relay, of course, remedied this.

[russiankid]

^ That is the exact reason why I did the relay setup. HID low beams and fog lights really draw a lot of current initially.

[slocar]

You may be w/o issues now, but the ballasts' toll on your stock wires is a slow-moving process...and I prefer to all-out avoid a bad situation. When I was test firing my retro w/o the relay wired in, my gauges would dip...which was a sign that the ballasts' start-up period was pulling more voltage than the e36 wires were designed for. The relay, of course, remedied this.

Yeah I get the gauge dip once every ... I dunno half dozen starts or less.

I guess I'm gonna wire up the harness tomorrow.

Thanks guys

[LockDots]

Guess i'll make my own and wire it up too lol. Thanks for kicking me to do it too guys!

[slocar]

Wired it up tonight; so far in the few start ups, no dip ... I did a fairly nice install except the part where the relay is and where all the wires sprout out of is just sort of all tucked in on behind the pass side headlight, but it looks alright.

[acastillo]

I don't think that spot in the engine bay sees too much water, but be sure to have the relay mounted upright, not laying sideways or upside down where water can collect.

On my M3, I've run an HID kit without harness for 5yrs now without failure. On my Odyssey, I've always run a harness and had 2 failures in 3yrs. Each time, the relay corroded and failed. This last time, the relay contacts were lubed in dielectric grease and sealed with electrical tape from the relay 4" down. Water still made it's way in. As of last week, I'm running without a harness.

[slocar]

It's right behind a headlight where the radiator support is bent down too; I've opened the hood after driving in torrential downpours before and never seen a single drop of water back there so it should be fine.

[russiankid]

I ran relays for my low beams and fogs light and I mounted the relays together. I have them right behind the drivers headlight like this : /\ . So if water does get there, it will drip right out.

[pbonsalb]

I have run 35w HID lows (plus AEs) on my 99M3 for several years of daily year round (rain, snow, etc) driving without issue. No relays.

[slocar]

Well honestly I didn't have any issues aside from the occasional gauge dip when I fire them up (which lasts all of a second), but I don't want to put any more stress on the thin/weak factory wiring than I have to, so I installed it. I figure for the 10 bucks I paid for it, and the 30 minutes of work, it's well worth it.

[coffee328]

Well honestly I didn't have any issues aside from the occasional gauge dip when I fire them up (which lasts all of a second), but I don't want to put any more stress on the thin/weak factory wiring than I have to, so I installed it. I figure for the 10 bucks I paid for it, and the 30 minutes of work, it's well worth it.

I'd say it's a worthy investment for the peace of mind; I'm glad you got it all wired up.

...and besides a preventative measure, the relay harness with thicker gauged wires helps ensure that the proper voltage reaches the bulbs.

[Ocelaris]

The reason to use a relay harness is to protect switches which are internal to the car, i.e. stalk or any other switch/ecu etc... from spikes. The current draw in the first few seconds is a large load, and in some cars inside stock switches can arc, and burn out switches over time. Using a relay physically seperates the current draw from the factory switches.

here's a nice little picture to demonstrate

[LuxoM3]

The reason to use a relay harness is to protect switches which are internal to the car, i.e. stalk or any other switch/ecu etc... from spikes. The current draw in the first few seconds is a large load, and in some cars inside stock switches can arc, and burn out switches over time. Using a relay physically seperates the current draw from the factory switches.

here's a nice little picture to demonstrate

[KOTULCN]

So I am a newb when it comes to wiring and I was wondering how the relay/fuse setup looks/goes together?

[3MPowered]

So I am a newb when it comes to wiring and I was wondering how the relay/fuse setup looks/goes together?

I'd also like to know this if anyone can help. Do you have to remove the OEM harness before installing the thicker guage harness?
Slocar would you by chance have any pictures of your install? It sounds nice and tidy.

[slocar]

Damn it my post went missing. Son of a ...

ok, this is where I hooked the wires to; pos to side of pos terminal, negative to the ground bolt behind strut tower:


I ran the wires down the fender with the washer fluid lines:


I ziptied the excess wire length for the pass side headlight behind the headlight itself .. .would be cleaner but DDMs harness is too long for its own good:


The wires for the driver's side I ran from the pass side under the radiator cover plastic, by ziptying them to the radiator support. They go in on one side:


And emerge on the drivers side:


The ballasts I put inside the bumper beam by means of double sided tape and only having the wires run to them and back:




Hope that helps ... and sorry for the post showing up and going missing ... i deleted it by accident oops

[3MPowered]

Thank you so very much, this is extremely helpful! My buddy was wondering the same thing, so this will go a long ways to helping him as well.

[LuxoM3]

FWIW - if you guys want to avoid the wiring harness mess - pull your bumper off and mount inside of it. LOTS of room. Bumper removal is 15min. AND A LOT drier than the engine bay. Please no heat soak issue either...

I'll post pics someday soon - car in shop now :\

[3MPowered]

Are you talking about mounting the balasts behind/inside the bumper carrier? There's no need to remove the bumper trim if so.

[LuxoM3]

Yep, pull the bumper off,... there's only 2-8mm bolts (wheel well) and 4-13mm (bumper) that hold the bumper on. Undo and you can see all the room you can use to mount/hide the wiring for the harness and HIDs.

One can mount the ballats INSIDE the bumper carrier. And you can run the wiring harness wires through the carrier too.

Aside from hiding the nest of wires better, the carrier gets A LOT less vibration and heat.

[3MPowered]

This is great advice! I had no idea taking off the bumper was that easy!

Thanks for the responses guys.

[G. P. Burdell]

Do you have to remove the OEM harness before installing the thicker guage harness?

The factory headlight harness is used to trigger the relay in the HID harness, so it has to remain in place.

[3MPowered]

Ah, thank you. Forgot I asked that