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Discussion Starter #1
I installed some Delta H4 headlights last week and once I'd worked out a few issues I got them running. On lo beam they were dangerously dim, so I tried some other H4 bulbs, but still the same. On hi beam they are great.

So I used a relay and ran power direct from the battery for lo beam, and there were still the same. Next step was to rewire the grounds, but still the same.

Now when I give it some gas (either at a stand still or pulling away) the lo beam dims down to nothing more than a candle. The voltage according to ScanGauge actually jumps up a little at the same time to around 14.0v (it usually sits at mid 13's.

This only happens on lo beam, which I wired direct from the battery, and not on hi beam.

I'm aware of the issues some have had with the delta quad lights, but this would appear to be a voltage/regulator issue, although I don't understand why.

Any ideas?
 

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Discussion Starter #3
No I didn't, but the trigger and + source are separated by the relay, but I'm guessing you are telling me I needed to?
 

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Discussion Starter #4
Okay I found your write up. I don't think a diode is needed, and I'm not sure the relay is opening the contacts as the lights stay on, just dim. They will stay dim for quite a few seconds, so I don't think the relay is opening. However I'll play with a voltmeter and see if there is any drop over the relay when it happens.

It's almost as if the battery is getting drawn down (as Scanguage is seeing a voltage increase) although it's a relatively new red top, or it could be a bad ground.

I'm half tempted to just go back to the stock wiring as I never had this issue then, and going through a relay off the battery didn't improve the light output anyway.
 

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yup
I just got all edumacated on this last week

This was my question thread, see if it sounds familiar...
http://www.jkowners.com/forum/showthread.php?t=10630

They go into the technical reasons behind the diode

Here's the write up I did afterwards
http://www.jkowners.com/forum/showthread.php?t=10665

problem is the canbus uses pulse madulated power to the lights to check and make sure they're working and that's no bueno to trip the relay
a 100uf capacitor smooths it out and the diode keeps from backfeeding the canbus
I thought a simple relay setup would work too but nope, gotta have that cap!

I bet a capacitor across your relay coil will fix it
 

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that is interesting Phil. If the voltage is going up but the light is dimming, wouldn't that suggest there is positive juice flowing back?

What I am saying is a incadesent bulb needs flow across the filament. I know this is obvious I am just kinda thinknig out loud.... If you hook up two power sources with the exact same power on each side of the filament it would not light because tehre is no flow.

Only way I know to dim a incadesent is by lowering the power. Either by a poor ground which you checked, or a poor power source which you checked...only other thing I could think is some sort of feedback. Maybe a diode would help???

PM John L. He is good with this sort of thing. I have no idea


EDIT: sorry, I am at work and started this reply a long time ago...looks like you guys already are figuring it out and that I was wrong anyway. I will just go back to sleep...I mean work
 

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I had the same problem, when I would come off of idle (volts go up), mine would dim, probably because the pulses by the canbus were shorter.
Voltmeter isn't fast enough to see the pulses it just sees an "average" of the voltage
you don't see the headlight pulsate because its a filament - you take power off and it will still glow for a sec, that residual glow covers the gap in the pulses
 

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Only way I know to dim a incadesent is by lowering the power.
or if you're feeding it very fast pulses of positive, slow or shorten the pulses :smokin:
 

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Discussion Starter #10
Hmmm, I'll try and see what is happening on the bulb side of the relay, and see if it is opening, but I can give it gas for 5 or 6 seconds and the lights go dim for that period. If it's opening I should hear it also.

The ScanGuage is seeing an increase in voltage at the same time, but I'm not exactly sure where it's seeing that, which makes me wonder if there is a drop at the battery.

Damn strange...
 

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Radio shack - $3 for the caps and give it a try,
easy to test and I will bet ya money it will fix it and save a bunch of tinkering
the scangauge is correct, your voltage is going up, but the canbus is modulating the power pulses to the relays to "make up for it"

to keep the juice at the lights the same all of the time, the computer will have to make shorter pulses when the voltage goes up, longer when it goes down.

the computer is trying to keep your lights the exact same brightness no matter what voltage, by modulating the width and frequency of the pulse for a happy medium - which relays don't like.
The capacitor nullifies the pulse and carrries the current through during the valleys in the pulse

I had the same problem, mine would dim when I gave it gas.
 

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Discussion Starter #12
They go into the technical reasons behind the diode
Okay, with a cap in place I can see for the reason for the diode.

I bet a capacitor across your relay coil will fix it
I'll give it a try and let you know.

It still doesn't change the fact I have really dim lo beams now though, but I'll see how it works when it's all done.
 

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It still doesn't change the fact I have really dim lo beams now though, but I'll see how it works when it's all done.
I dunno for sure, but I'm willing to bet something is confusing the heck out of the 'puter and making it very unhappy
you'll need the caps anyway so I would try installing them first and see if that fixes low beam.
Since they're gonna be needed anyway, may as well see if they help

just spitballing here, but if the puter pulses the negative instead of the positive, or if it pulses both, low beams being on the relay and not highs will show some serious imbalance, it may also be looking for resistance on the low beam through the ground and see the difference between the two and think your headlight is out and be trying to cut power to it.
All it would need to do is on start up send a pulse to the high then to the low and check resistance
 

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Oh yeah, and if it helps any - the light output afterwards is worth the effort :grinpimp:

especially if you pick up a pair of hella 55/100 bulbs for less than $20
55w low beam is still tame and won't blind oncoming traffic, but the 100w highs are GREAT.
 

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Discussion Starter #16
What do you know the dimming stopped :)

Thanks for the help, really appreciated!

I'll see how bright (or not) they are tonight.

Thanks again.
 
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