Custom headlights - help!

[danmc77]

Ok, this is for all the electric gurus out there...

I have converted to HID headlights on my 68 Charger.  I thought I had all the wiring figured out, but I was looking it over and I see a problem.

Ok, on a stock setup, there are 2 wires that control the HI and LOW beams that come from the foot selector switch; one violet(low), and one red (high).  The way the system works is that for low beams, just the low bulbs are illuminated.  When the HI beams are activated, the LOW bulb has a second filiment that lights and the HI bulbs come on as well.  The Low bulb has 3 terminals on the back (GND, HI, and LOW - basically 2 bulbs in one), while the HI has only 2 (HI and GND).  

Now, the problem is that the HID bulbs that I have are essentially low beams with only one function.  My intention was to use 2 sets, and when the HI beams are selected by using the foot switch, all 4 HIDs would be illuminated.  I figured that would be plenty of light and no real need to use HI/LOW specific bulbs.  The stock system allows the low bulbs to act as a HI bulb with a second filiment - so the HI wire (red) is connected to the back of both stock bulbs.  How can I wire 4 2-wire bulbs to work like the originals; 2 outside for the LOWs, and 4 (inside and outside) when HIs are on?  

Initially, I thought I could basically just wire the red to the bulb that would be acting as the HI, and the violet to the LOW bulb, but that would just alternate bulbs from one to the other rather than illuminating all 4 when the selector is activated.  

Any suggestions?

[c00nhunterjoe]

yup, time for a quick re-wire. leave the low beam wire as it is sotck and take the factory high beam wire and spilt it out near the head lights, pigtail it so that the high beam wire splits to all 4 bulbs, it may be safeer to use relays for the high beam so as not to overload the wires with 4 hid strikes

[danmc77]

yup, time for a quick re-wire. leave the low beam wire as it is sotck and take the factory high beam wire and spilt it out near the head lights, pigtail it so that the high beam wire splits to all 4 bulbs, it may be safeer to use relays for the high beam so as not to overload the wires with 4 hid strikes

The problem is, if the HI beam wire has to be wired to both bulbs, that would mean that the LOW bulb would have both the LOW and HI wires on the same terminal.  If that's the case, wouldn't all bulbs be energized regardless if I click HI or LOW on the selector?  Remember, the new bulbs, both HI and LOW, only have 2 terminals each - basically power and ground.  I need to figure out how to have 2 bulbs illuminate wiht one "power" wire (Low), and 4 bulbs to work with the other "power" wire (HI).

The HI beam is simple - just hook the HI power wire to all 4 bulbs - all 4 will illuminate - which is what I want.  the problem is if all the bulbs are wired together, how do I get 2 bulbs not to illuminate when the LOW power wire is activated?

[danmc77]

OH!  I think I figured it out.  I don;t know anything about electronics, so people who do know, please let me know if this works or not.

If I understand correctly, a relay is a switch activated by a 12v signal, like the original headlight power wire.  Once the switch is activated, it directs power directly from the source, rather than through the "signal" wire.  If that's the case, unless the relay is activated, the switch is open, right?  No power through it?

If that's the case, I can use that to my advantage.  If I run 3 relays, I can effectively separate the HI and LOW beams - I think.  With 2 relays (HI and LOW) the HI realy will have to be connected to both HI and LOW bulb to illuminate all 4 bulbs when activated.  the problem is that the LOW bulb will then have both the LOW and HI relays connected to it, so all 4 bulbs will be illuminated regardless of whether I have selcted HI or LOW from the foot switch.  If I add a third relay, I think I can separate the bulbs.  

This is what I'm thinking...

The LOW will go through a single relay, wired to the LOW bulb only.  With the HI power wire, I split it to activate 2 relays.  The one will power the HI bulb alone.  The other will be connected to the same LOW terminal that the LOW realy is connected to.  However, because the relay doesn't flow unless the "signal" wire is energized, it will act as a wall to block any electricity from reaching the rest of the HI circuit, and therefore the HI bulb, when the LOW is activated.

Does that work?

[2Gunz]

It would work if they where "normal" bulbs.

But Since they are HID the toggle time between high/low might case them to go out.


The better way to do this is to tap into the line before the High/lower switch.

I didnt look at the wiring diagram but logic would suggest that the circuit is like this...

Battery
Fuse box
Light switch
High/low switch
headlight


So just get the low beam relay power before it gets to the High/low switch.
Then get the High relay power after the high/low switch.

Basically you get power all the time for the low beams when the healight switch is turned on.
Then the High/low switch just becomes a toggle for the other lights.


Anyway the flaw I see in this is that the high beams wont be instant on because they need to strike and warm up.

Good luck

[danmc77]

2Gunz - great idea about using the toggle to just activate the HIs.  That sounds like the right way to go - thanks!

As far as the delay to start up the HI's, I'm not too worried about it.  It's literally a matter of seconds for the bulbs to ignite and warm up - I can live with that.  In addition, I just want it to be functional, I really don;t plan to do too much night driving anyway.  And in that case, with the HID lows, I may never need the HIs anyway.

Thanks!