H4 dual filament HID question

[CorvallisBMW]

After contacting DDM about HID bulbs for the H4s, they say that I need a 2 filament bulb. So I pull the stock bulbs to take a look and sure enough, they have 2 filaments. But the DDM dual filament bulbs are 4x the price of the singles ($25 for the pari vs $100 for the pair), so I decide to order the singles and hope for the best. When they arrive I install them and they work great. But when I turn on the highs, the lows turn off and I have no short-distance visibility. With stock bulbs, the lows stay on when the highs are turned on.

It seems like the HID lows should stay on too then, whether they are dual filament or not. But for some reason they don't. Is there a relay or pin I can jumper to force them to stay on, or am I stuck paying a bunch of $$$ for dual filament HID bulbs?

[smonkbmw]

maybe try the relay jumper trick to get the lows to stay on with the highs. when you add us elips to a car that doesnt have them you get this same problem.

[CorvallisBMW]

maybe try the relay jumper trick to get the lows to stay on with the highs. when you add us elips to a car that doesnt have them you get this same problem.

which pin on which relay? wouldn't it already be set up this way if they stay on with stock bulbs?

[StereoInstaller1]

I would think the heat of having both filaments on at the same time would smoke them quickly, or perhaps melt the housing.


Keep me posted as this develops though, would ya? I am doing HIDs on a '37 Plymouth, soon, and want to use the Miata projectors.

[///M42 sport]

Why H4's? I thought euro ellipses fit H1's? If this is incorrect, then the FAQ post about lighting is not correct.

[CorvallisBMW]

I dont have euro ellips

[2002maniac]

which pin on which relay? wouldn't it already be set up this way if they stay on with stock bulbs?

they stay on with the stock bulbs because the stock H4 bulbs are dual filament. one for highs, one for lows.

you may be able to trick the low beams to turn on when the high's come on by jumpering the relay but I'm not sure it will work.

let us know

[gearheadE30]

I'm considering HIDs for my H4 setup as well, and I can't think of much of an idea except hook all three wires to the bulb, but put diodes on them to prevent reverse current. Of course, I suck at electrical stuff, so I wouldn't try that without a professional opinion.

Keep us posted, I want to see how this goes.

[CorvallisBMW]

I'm considering HIDs for my H4 setup as well, and I can't think of much of an idea except hook all three wires to the bulb, but put diodes on them to prevent reverse current. Of course, I suck at electrical stuff, so I wouldn't try that without a professional opinion.

Keep us posted, I want to see how this goes.

hmmmm, interesting idea. I too know very little about electronics, so perhaps I will have Luke look it over when I head down there for a stereo install

[gearheadE30]

Any news on this?

[CorvallisBMW]

Bulbs should arrive by FedEx today, so I'll work on it this week and keep the thread updated. I know some of you guys are really interested, and I dont blame you. I can't see why a pair of single filament bulbs costs $25 but a pair of dual filaments cost $100, wtf mate.

[Fidhle007]

You're having the same issue you would have if you installed euro elips with H1 bulbs on your car. If you're running a single filament bulb you can jump pins #30 on the low and high beam relays to keep them on. This will also keep your fogs on with your highs for whatever that's worth...

[CorvallisBMW]

^ damn I wish I had seen your post last night Fidhle, I would have tried that. I'll try that first, and if it doesn't work I have a few other possibilities listed below.

Here's what I found out from my little expiriment last night:

Normal H4 bulbs are dual filament, with one filament (hereby referred to as "low-beam filament", not to be confused with the whole low beam bulb) burning while your low beams are on, and the other filament (hereby referred to as the "high-beam filament", not to be confused with the H1 high beam light/bulb) burning when your highs are on (in addition to the H1 highs themselves). The low beam wiring harness has 3 sockets: one for the "low-beam filament", one for the "high-beam filament", and one for ground.

When you turn on your low beams, 12V goes only to the "low-beam filament" socket. When you activate your high beams, 12V goes only to the "high-beam filament" socket.

The DDM HID kits only come with 2 wires, which mean you can only have the HID headlights running when the lows are on OR when the highs are on. Not both, as swtching between high beams and low beams disrupts where the 12V is going. So I spliced the wiring harness to connect the "high beam filament" and "low beam filament" wires, hoping to trick the HIDs in to staying on when the highs are activated. It works!! But of course since electricity travels both ways, and I've fooled the relay in to thinking the HIDs are running as high beams, it means the high beams (the H1s) stay on all the time, whether the high beams are switched on or not.

Confusing yet? Sorry, I'm not too great at technical writing.

My idea is to splice an extra connector on to the 12V wire coming off the HID bulb, and plug them in to both the "high-beam filament" and "low-beam filament" sockets on the H4harness. This will make them just like the 3-plug H4 bulbs you would normally use, and it should allow them to get power whether you have your highs or lows switched on in the car.

I will continue to work on it and post updates as I find out more!

[TheEtaUnderdog]

^ damn I wish I had seen your post last night Fidhle, I would have tried that. I'll try that first, and if it doesn't work I have a few other possibilities listed below.

Here's what I found out from my little expiriment last night:

Normal H4 bulbs are dual filament, with one filament (hereby referred to as "low-beam filament", not to be confused with the whole low beam bulb) burning while your low beams are on, and the other filament (hereby referred to as the "high-beam filament", not to be confused with the H1 high beam light/bulb) burning when your highs are on (in addition to the H1 highs themselves). The low beam wiring harness has 3 sockets: one for the "low-beam filament", one for the "high-beam filament", and one for ground.

When you turn on your low beams, 12V goes only to the "low-beam filament" socket. When you activate your high beams, 12V goes only to the "high-beam filament" socket.

The DDM HID kits only come with 2 wires, which mean you can only have the HID headlights running when the lows are on OR when the highs are on. Not both, as swtching between high beams and low beams disrupts where the 12V is going. So I spliced the wiring harness to connect the "high beam filament" and "low beam filament" wires, hoping to trick the HIDs in to staying on when the highs are activated. It works!! But of course since electricity travels both ways, and I've fooled the relay in to thinking the HIDs are running as high beams, it means the high beams (the H1s) stay on all the time, whether the high beams are switched on or not.

Confusing yet? Sorry, I'm not too great at technical writing.

My idea is to splice an extra connector on to the 12V wire coming off the HID bulb, and plug them in to both the "high-beam filament" and "low-beam filament" sockets on the H4harness. This will make them just like the 3-plug H4 bulbs you would normally use, and it should allow them to get power whether you have your highs or lows switched on in the car.

I will continue to work on it and post updates as I find out more!

relays are your friend...

[Fidhle007]

Yeah, this has been pretty well documented already by guys swapping euro H1 setups into sealed beam cars (sealed lows are the same as H4s) and it's been verified that making a two lead harness doesn't work. Just jump the relay pins I told you to and call it a day, it's the safest and easiest.