Fan and Headlight Relays
Pro
Joined: Nov 2000
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From: Tucson AZ
Originally Posted by I'm Batman
That is some impressive work on that harness. 
Craig
Race Director
Joined: Feb 1999
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From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
The headlight relays are the way to go. It is only a matter of time til something happens to the stock headlight switch. When I bought my car it had its headlight switch meltdown at one point and damaged the dash pad. My cars speedometer and tach were full of white powder from a fire extinguisher where someone tried to put it out. I keep saying I am going to add these relays to my car but have never got around to it. It is actually on my list of things to do this winter. Plus I am going to book mark this thread as a reminder.
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
I'm getting ready to do teh relay thing for the headlights, and for the fan. For the headlights, I've decided I want all four on all the time, and on low beam. I don't use brights ever, so I am using H4 singles. I was wondering how many amps four H4 halogens will use while all connected and all four running at the same time. I want to use a single relay for simplicity, and because all are teh same and all on att eh same time. Would they all run off of a single 30 amp relay, or should I buy another 75 amp relay when I order one for the fan?
Thread Starter
Safety Car
Joined: Nov 2005
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From: Lompoc, CA. Santa Barbara County
Originally Posted by Durango_boy
I'm getting ready to do teh relay thing for the headlights, and for the fan. For the headlights, I've decided I want all four on all the time, and on low beam. I don't use brights ever, so I am using H4 singles. I was wondering how many amps four H4 halogens will use while all connected and all four running at the same time. I want to use a single relay for simplicity, and because all are teh same and all on att eh same time. Would they all run off of a single 30 amp relay, or should I buy another 75 amp relay when I order one for the fan?
Melting Slicks
Joined: Nov 2001
Posts: 2,668
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From: Eastern US XX
Originally Posted by DWncchs
Paul do you think relays from the factory would have been an improvement or was the original way OK until the system got some time on it and connections started building resistance?Should GM have put in heavier wire to carry more load?Surely the GM engineers would have wanted the lights to be as bright as possible.Hmmm maybe it was just a production cost issue and the lights were "good enough".
Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
Originally Posted by Durango_boy
I'm getting ready to do teh relay thing for the headlights, and for the fan. For the headlights, I've decided I want all four on all the time, and on low beam. I don't use brights ever, so I am using H4 singles.
Also if the 4 are adjusted so they all point down at the front of the car so again they don't blind others you can outdrive your lights. Running across country at high speed you need all the distance you can get.
I wouldn't do it. Install the relays to brighten the existing lights, keep highs and lows seperate and don't skimp on the relays. They are only $5 each and you need 2 PLUS fuses.
Mine is not as neat as yours and I would have loved the remale plugs but couldn't find them. I run one for high and one for low plus 2 30 amp fuses
Last edited by norvalwilhelm; Sep 26, 2006 at 09:31 AM.
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
Originally Posted by Durango_boy
I'm getting ready to do teh relay thing for the headlights, and for the fan. For the headlights, I've decided I want all four on all the time, and on low beam. I don't use brights ever, so I am using H4 singles. I was wondering how many amps four H4 halogens will use while all connected and all four running at the same time. I want to use a single relay for simplicity, and because all are teh same and all on att eh same time. Would they all run off of a single 30 amp relay, or should I buy another 75 amp relay when I order one for the fan?
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
Originally Posted by pws69
Actually, I believe you will run into legal issues doing that. Basically it can be construed as a malfunction of your headlights if you can't switch from high to low beam. Check your local regs.
I asked around a while back when I forst thought of doing this, and there seemed to be no rules saying a car had to have brights. I understand I will probably get a few flashes, but with as many cars running these days with four running headlights, foglights, and then the idiots that drive with no llights or both lows ands brights on...I'm not too concearned I annoy people.
The outer lights will have a slightly outward aim...nothing drastic or into other lanes...I just want some extra dimension to the beam. The inners will have a slightly higher aim than lows but still be lower than the highs.
I just wanted to know how many amps 4 H4's will draw. I have no problem springing for the extra relays, but I would like to keep the number down to keep things neat and tidy.
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Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
Originally Posted by Durango_boy
I just wanted to know how many amps 4 H4's will draw. I have no problem springing for the extra relays, but I would like to keep the number down to keep things neat and tidy.
It is just as easy to mount 2 as one and getting enough wires, sure you can splice further down the line but each relay as only one output and one input. Two smaller wires are easier to work with then one extra large one carrying 50 or 60 amps.
I like dual everything, like a plane, dual fans, each on a seperate relay, dual fuel pumps again on seperate relays.
You can get up to 100 amp relays but then you also have to deal with # 6 or # 8 wire. #10 is rated at 30 amps maximum and you will be pushing more then that.
Team Owner
Joined: Oct 2004
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From: Springfield MO
St. Jude Donor '07
As long as all four of them are hi/lo H4s, I don't see it being much of a problem, just severe overkill. H4 bulbs have the deflector in them to keep light out of the eyes of oncoming drivers on lo beam, so I don't think it will be that irritating.
Norval, you should know as well as anyone that the hi and lo beams aren't separate - at least on the outside bulbs.
If the lo circuit is the standard 55w range, four bulbs would pull less than 19 amps by my seat-of-the-pants calculation.
Norval, you should know as well as anyone that the hi and lo beams aren't separate - at least on the outside bulbs.
If the lo circuit is the standard 55w range, four bulbs would pull less than 19 amps by my seat-of-the-pants calculation.
Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
I had the bright idea in the beginning to leave my low beams on when I switched to high beams, afterall it would almost double the light output from a bulb but then I got to worrying about overheating the bulb. Was the bulb designed to handle high and low on at the same time and all the extra generated heat??
On my dodge truck if you hold the switch between high and low you get both lights on at the same time and it really brightens up the night.
Drove 3 or 4 miles with the switch held in the central position then burned everything out. Really smart on my part.
On my dodge truck if you hold the switch between high and low you get both lights on at the same time and it really brightens up the night.
Drove 3 or 4 miles with the switch held in the central position then burned everything out. Really smart on my part.
Team Owner
Joined: Oct 2004
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From: Springfield MO
St. Jude Donor '07
I wouldn't turn on both circuits at once, but the H4 is a three-prong bulb - two filaments - one for hi, one for lo. It wouldn't be hard to wire up the four lo filaments the same way as the standard four hi filaments.
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
Also, I really could care less about other people thinking I have on my brights. If I don't, they have nothing to really complain about. I'm doing it for a few reasons other than looks. True, I like the way it looks with four lit instead of two...but the big reason is visibility. Here, at night, you have a high risk of dear hits. They just wander out onto residential streets, and if you're not prepared or don't have enough warning...WHAM. Deer jerky for a year and a lot of body work. 
Pro
Joined: Nov 2000
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From: Tucson AZ
Originally Posted by norvalwilhelm
but each relay as only one output and one input. Two smaller wires are easier to work with then one extra large one carrying 50 or 60 amps.
May I suggest a Bosch relay #0-332-019-110. It has one input and two outputs and is rated at 40amps. It makes things a little easier to wire
.
Craig
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
Originally Posted by VetteNut72
Norval,
May I suggest a Bosch relay #0-332-019-110. It has one input and two outputs and is rated at 40amps. It makes things a little easier to wire .
Craig
May I suggest a Bosch relay #0-332-019-110. It has one input and two outputs and is rated at 40amps. It makes things a little easier to wire
.Craig
Ooh that's
. Where isa good place to get those? Locally or would I have to order some? I will also need a 75 amp relay, and would like to get them all in the same place.
Team Owner
Joined: Oct 2004
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From: Springfield MO
St. Jude Donor '07
Racer
Joined: Mar 2005
Posts: 473
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From: Champlin Minnesota
Originally Posted by Durango_boy
Ooh that's . Where isa good place to get those? Locally or would I have to order some? I will also need a 75 amp relay, and would like to get them all in the same place.
. Where isa good place to get those? Locally or would I have to order some? I will also need a 75 amp relay, and would like to get them all in the same place.
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
Originally Posted by davidm_comp
I just picked up a 40 Amp relay last night at my local Napa, though I bought if for my fuel pump, it will still work for headlights. I also got the plug w/wires, came to $18 total. It looks exactly like the one in the diagram, has 2 outputs, 12 V in, switched power, and a ground.
Do they sell 75 amp relays?
Racer
Joined: Mar 2005
Posts: 473
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From: Champlin Minnesota
I did not see them, but I did a yahoo search and came across a 4x4 forum. Guys on it had a thread talking about headlight relays, someone said they bought a 75 amp relay at napa. But if it were me, I would go with two 40 amps, you can get them everywhere over the counter, even Walmart, and if one goes out you will still have some working headlights.