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Unread 12-05-2006, 07:27 PM   #1
badtux
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100 watt H4 headlight bulbs with stock harness

Thinking about the Hella e-spec 7" H4 conversion and the 55/100 watt bulbs. There's a 40 amp fuse for the exterior lights, and less than 30 amps being used, so it looks like the circuit will take the 100 watt bulbs. This is only 70 watts (less than 6 amps) more than stock, after all.

The only question after that is whether this would exceed the capacity of the headlight relays. Has anybody done this mod without fabricating a relay kit?

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Unread 12-05-2006, 07:53 PM   #2
Jerry Bransford
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There is no headlight relay, all that current goes right through the headlight switch. The OE harness will support 100w bulbs but not continually, it's marginal at that much load. I finally installed a headlight harness that uses a relay for both headlights with a direct heavy lead right to the battery and the lights are definitely brighter with zero load on the OE wiring harness. It's a plug-in mod that I highly recommend.
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Unread 12-05-2006, 07:55 PM   #3
RnEmOvr
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i made one for my buddies YJ and we tested it, the side with harness on low was as bright if not brighter then the factory side on high, i had the relays laying around but you could make one for about $5-$10 if you know how to wire a relay
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Unread 12-05-2006, 08:00 PM   #4
badtux
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Thanks, I have a couple of relays hanging around, guess I'll have to use them :-(. All that power's going through the headlight switch. Huh. That's... hmm... what's that word I was searching for, again?
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Unread 12-05-2006, 08:02 PM   #5
RnEmOvr
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Quote:
Originally Posted by badtux
Thanks, I have a couple of relays hanging around, guess I'll have to use them :-(. All that power's going through the headlight switch. Huh. That's... hmm... what's that word I was searching for, again?
retarded on DCs part
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Unread 12-07-2006, 10:50 AM   #6
Traceycon
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Resistance. too much will melt the harness and the headlight switch.
Build a relayed harness.
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Unread 12-07-2006, 10:54 AM   #7
Jerry Bransford
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Quote:
Originally Posted by dzntzhellfire
retarded on DCs part
Few automotive manufacturers use relays for standard headlights. In fact, of the 30+ cars/Jeeps I've owned, I recall just one (a Lexus LS400) that may have used a relay for the headlights.
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Unread 12-07-2006, 10:55 AM   #8
JBTJ
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Quote:
Originally Posted by Jerry Bransford
There is no headlight relay, all that current goes right through the headlight switch. The OE harness will support 100w bulbs but not continually, it's marginal at that much load. I finally installed a headlight harness that uses a relay for both headlights with a direct heavy lead right to the battery and the lights are definitely brighter with zero load on the OE wiring harness. It's a plug-in mod that I highly recommend.
Jerry, do you have a write up on how this is done? For what it's worth, I have a 01 model.

Thanks
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Unread 12-07-2006, 10:57 AM   #9
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Quote:
Originally Posted by JBTJ
Jerry, do you have a write up on how this is done? For what it's worth, I have a 01 model.

Thanks
Once you receive the relay wiring harness, you'll see that it's strictly a plug-in modification. Unplug the OE harness from the headlights, plug the relay harness in between those two plugs you just unplugged, and run one wire to the battery. It's very easy to install. No 'lectrical knowledge needed.
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Unread 12-07-2006, 11:03 AM   #10
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Quote:
Originally Posted by Jerry Bransford
Once you receive the relay wiring harness, you'll see that it's strictly a plug-in modification. Unplug the OE harness from the headlights, plug the relay harness in between those two plugs you just unplugged, and run one wire to the battery. It's very easy to install. No 'lectrical knowledge needed.
Easy enough, were does one obtain this harness?
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Unread 12-07-2006, 11:06 AM   #11
Jerry Bransford
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Here's where I got mine... http://www.suvlights.com/index.php?c...52de6faacf3db3
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Unread 12-07-2006, 11:11 AM   #12
JBTJ
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Quote:
Originally Posted by Jerry Bransford
Universal Wire Harness (9003/H4, 9004/HB1, 9005, 9007, H7/H1, H7/H7)
$63.00/Each

That one, Jerry?
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Unread 12-07-2006, 11:39 AM   #13
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This sounds so much like a discussion on the DeLorean headlight switch it isn't even funny. The headlight switch on a DeLorean is pretty simple, push it once and marker lights and dash illumination lights come on. A second push turns the headlights on. A third push and it all shuts off. But one little problem, it was all ran through the switch! The plastic inside the switch would melt and eventually, you'd have to switch. A few people have come up with a relay you splice into the harness to save the switch from this fate. My switch started showing its signs of this. Afyter driving for a while with the lights on, turn them off, try to turn them on again and the switch wouldn't stay in the "on" position. I'd have to wait for it to cool off. The inventory for DeLorean headlight switches has been exhausted but DeLorean Motor Company in Texas has some new ones being made for us with a digital control box that has the power bypassing the switch and it also has an auto off feature. I'm still waiting on my new switch that I preordered last year.

Anyway, after reading this thread, when I update to H4s on my TJ, I'll do the harness mod. just as a precaution. I may even do it before. Thank you for that link Jerry!

is the fog lights wired up in the same manner and is it worth doing something for them too?
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Unread 12-07-2006, 05:18 PM   #14
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do you have any wiring skills? if so here is a writeup fo you to build your own.
http://go.jeep-xj.info/HowtoHeadlightLoom.htm
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Unread 12-07-2006, 07:16 PM   #15
Jerry Bransford
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Quote:
Originally Posted by conundrum1984
is the fog lights wired up in the same manner and is it worth doing something for them too?
The OE fog lights run off a relay so they're ok to be upgraded to something brighter... within reason of course.
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