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LMC 4 headlight harness upgrade + Painless low + high headlight kit setup questions

all you need for all 4 of the lights working when the hi's are on when you do the relay mod is to ditch the factory light switch and run a DPDT (I run an off/on/on)
 
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Mountain_man said:
I've looked everywhere and can't find any other place that sells the same headlights as a suburban's quad light. Anyone find something that I'm missing? '91 sub share headlights with other vehicles?
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Do your Burb's lights look like those? It's the setup I've been talking about this whole thread.:D LMC and www.EuroLights.com along with everyone else mentioned carry those.
 
Blue85 said:
But the point of the relays is to make the lights brighter by reducing voltage drop. Powering a bulb through a diode has the opposite effect - it reduces the voltage to the bulb. You should at least use a schottky.
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As you likely know, a diode limits/eliminates current in one direction. For this application you want to use the diode to "share" the high beam signal with the low beam relay coil, but prevent the low beam signal from reaching the high beam relay coil... the diode allows this.

Or, as Ryoken stated, you could ditch the factory switch for a DPDT to accomplish this.

Or, you could use another relay that takes the high beam signal as an input and it's output runs to the low beam input relay... if you will.

I didn't have to ditch any factory wiring, didn't have to create any harness... and spent like $33 total. That's why I went the LMC harness/diode route.
 
sandypants said:
these are great upgrade. :Di got the lenses on ebay for 9.99 a pair and bulbs that were white not the freaking blue(had to search for white tent only) but the white is brighter they were 90/110 and is awsome. all on ebay. but i did get the wire harness from lmc and its deffinitly a great upgrade. everything just plugs in and two wire go to you batt. so its easy and probably on of my top 5 upgrade. :D:D:D:D
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I'm looking to upgarde mine as well. Can you foward the ebay sellor info?
 
bigdogkrug said:
Dremu, I wanna do that diode thing you mentioned to get the low beams on with the hi beams. Can you help me get it installed? I live in Newark so I'm close to Concord.

Jerad
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(I apologise in advance to AJM for the tangential semi-hijack :D )

The diode trick only works if you have already done the relay thing. LMC sells a kit for this...

http://www.lmctruck.com/icatalog/bzc/full.aspx?Page=62

(bottom left corner)

...or you can do it yourself:

http://coloradok5.com/forums/showthread.php?t=164429

If your wiring is stock, then you'd need a kit to have the highs and lows come on together, which oddly, consists of a relay =))

http://www.summitracing.com/parts/SUM-890300/

for example (may not be specific to your truck.)

At that point, you're halfway to the relay job in terms of cost, and a third of the way in terms of re-wiring, so you may as well just do the whole enchilada. IMO.

I'm happy to help, once you decide whatcha wanna do. There are some other folks in the area, though I can prolly claim to be the most electrical-geeky :D

-- A
 
Andrew I'd help but I did mine with a bunch of stuff scrounged out of a junk yard. I think I had 10 bucks in all of it. But mine has single bulbs.
 
Oh, ok... so need to decide which way to go... I have just sealed beam halogens in there now... you think doing the relay kit will make them much brighter? I'd like to do the euro conversion but no money right now... So I'm leaning towards the relay re-wiring...
 
I would guess that is because the quad headlights have an oddball connector that I haven't been able to find. The euro-conversion probably uses a standard connector.
 
bigdogkrug said:
Oh, ok... so need to decide which way to go... I have just sealed beam halogens in there now... you think doing the relay kit will make them much brighter? I'd like to do the euro conversion but no money right now... So I'm leaning towards the relay re-wiring...
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My .02 is to do the rewiring first, as it'd benefit any later modifications you make. Certainly can't hurt.

-- A
 
driney said:
I would guess that is because the quad headlights have an oddball connector that I haven't been able to find. The euro-conversion probably uses a standard connector.
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the Euro-conversion headlights SHOULD be using the newer "9000" series of replacement bulb, the bulb itself is removable from the rear of the housing (which is composite) like most all of the newer vehicles with composite headlights. Those use a weatherpac style plug anyways, totally different than what is on our rigs to begin with... my guess is it has something to do with the actual plug/harness that connects at the firewall going to the fuse box.

i have mentioned earlier that i did the relay connection for my low beams to come on WITH high beams, i did nothing as alot of guys are commenting about making headlights in general "brighter" as i felt these style of headlight are plenty bright enough when they are adjusted properly, BUT when the high beams are on, WITH the low beams, it is a world of difference with all four on now. :D
 
"I then put a diode pointing from the factory harness "hot" for the brights to the factory harness "hot" for the low beams (this setup is easy and clean in my opinion but you could accomplish it with another relay too).

MUCH, MUCH better with the low beams on when the brights are selected in my opinion."

this was from blazerbones post earlier in this thread , has anyone else done this mod?? or any other mod to make the high and low beams come on at the same time when the highs are activated?? if so could you go into a little more detail about the mod ? (where to put the diodes , how many diodes , what size diodes ect. or how it would be done with a relay as mentioned? a simple wiring diagram would be a great help at the very least as i want to do this upgrade with the original haogen lights after upgrading to the silverstar halogens , i did the LMC harness upgrade today , thanks for any help you guys can offer as i am not really that knowlegable as far as electrical work is concerned!
 
carolinafan4life63 said:
has anyone else done this mod?? or any other mod to make the high and low beams come on at the same time when the highs are activated?? if so could you go into a little more detail about the mod ? (where to put the diodes , how many diodes , what size diodes ect. or how it would be done with a relay as mentioned? a simple wiring diagram would be a great help at the very least as i want to do this upgrade with the original haogen lights after upgrading to the silverstar halogens , i did the LMC harness upgrade today , thanks for any help you guys can offer as i am not really that knowlegable as far as electrical work is concerned!
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Just one diode. Technically best described as pointing from the high beam relay coil exciter wire to the low beam relay coil exciter wire.
 
Hey Carolina fan, What year is your Blazer? I tried to get new SilverStars (Sylvannia) halogen headlights for my 90 k5 and couldn't find them... I know they make them for the 88 and older trucks, but mine takes the smaller H4701 series bulb... just wondering cause I'd love to install the SilverStars... They are great lamps...

To all... Is it possible to make the bights and lows come on without using a relay setup???
 
dremu said:
No no no.

You use the diode to energize the coil of the low beam's relay. The relay then transmits full voltage to the low beams.

Not like you're gonna get 10A through a 1N4001 :haha:

-- A
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Yes, you're agreeing with me, but apparently didn't understand what I said. It sounded to me like Blazerbones was just powering the low beams through a diode to save the cost of a relay or something. You could make it work with a low-voltage drop, high-current diode (similar to a battery isolator), but the proper diode would actually cost more than a relay and perform worse. Plus, you would make the headlight switch fail sooner.

From Wikipedia:
The Schottky diode (named after German physicist Walter H. Schottky; also known as hot carrier diode) is a semiconductor diode with a low forward voltage drop and a very fast switching action.

Sorry if my posts are confusing, I guess basic stuff like this just seems obvious to me :dunno:
 
Blue85 , could you possibly explain to me how to wire up a relay so that all 4 headlights come on when the high beams are activated ? i just installed the LMC heavy duty harness yesterday , thanks
 
carolinafan4life63 said:
Blue85 , could you possibly explain to me how to wire up a relay so that all 4 headlights come on when the high beams are activated ? i just installed the LMC heavy duty harness yesterday , thanks
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It's easy. Assuming that the LMC setup has two relays in total, all you need is one diode. The relays must have one leg grounded and the other leg connected to the headlight switch(es). You want to put the diode between the two relay coils, with the stripe pointing towards the low beam relay. This will be terminal 85 or 86 on most relays, whichever one is not connected to ground. Maybe somebody who has the LMC harness can tell you what color that wire is.
 
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