One More Headlight Relay Thread

[TR65]

Guys,

There are a number of good headlight relay conversion threads on the board. Here are a few of them:

http://67-72chevytrucks.com/vboard/s...elay+headlight

http://67-72chevytrucks.com/vboard/s...elay+headlight

http://67-72chevytrucks.com/vboard/s...ight=headlight

I am going to add one more based on my recent experience. My headlight switch failed after I installed halogen bulbs in the truck so it was time to go to relays.

I started with a heavy duty headlight harness from LMC Truck #36-3580 ($30). It includes the relays and new headlight lamp connectors. It also has power wire connectors and plug in connectors to the relays. The connector that is supposed to hook to the stock truck wiring is not correct for our trucks and is of no use.

I cut the harness apart and reworked it as shown below. It is a good starting point.

Works like a champ. My next step is to convert from sealed beam to H4 bulbs in Hella E-Code Reflector lamps as explained by Rogue in this thread.

http://67-72chevytrucks.com/vboard/s...d.php?t=395480

TR

[TR65]

The rest of the Pics.

[Sick5]

looks good
THANKS

[astrochimp]

Nice job!

And great photos too.

I got my headlights here-

http://store.candlepower.com/fco7h4mohebd.html

"This premium genuine Bosch 7" (180mm) headlamp lens-reflector unit is DOT certified to the SAE J584 motorcycle headlamp"

[TR65]

Got my Hella E-Code H4 reflector lamps and I used Hella H4+50% halogen bulbs. They are bright. There is a very distinct horizontal line that cuts the light off to keep glare down on the low beams. The Hella Lamps have flat fronts instead of the rounded front sealed beams. The pair draw 9.8 amps low and 10.9 amps high. (See Rogues link above)

The next step would be Xenon HID bulbs and ballasts in the E-Code reflector lamps if I am not happy with the halogens in the future.

My wife has an Audi A4 with HID headlights and they are really remarkable. You put those babies on high beam and you can see all over. They only draw 35 watts. The lamps are motorized and follow the terrain to keep glare down for oncoming drivers. They also turn left and right following the steering.

TR

[markeb01]

Sure looks like a clean setup. Did you have to do any modifications to the headlight buckets or radiator support to install the lamps? Also how do you change the bulbs? Do you pull everything out the front like a conventional sealed beam? Also where did you get your lamps/bulbs, and were you happy with the deal.

I drive with my lights on all the time, so I'm still running old school normal power sealed beam lamps for low beams, with halogen sealed beams for the high beam lamps (1960 4 lamp system). I use to run halogen sealed beams but they burned out so often I went backward on light power to avoid the chronic replacements. I'd like to upgrade to H4 bulbs as well, but I'm concerned how much modification is needed to mount them, or the amount of effort required to replace the bulbs.

[62 short step]

Do the relays need to be used for the stock wiring harness? Is that the problem?

[TR65]

Markeb,

The lamps are a perfect fit to replace our sealed beams. They work perfectly in the buckets and locate the same way. There is a rubber seal for the rear. The bulbs come out of the rear. The H4 connector is the same as on our trucks. No modification is required at all. Change em out and plug them in.

Here is where I got mine (they seem like good guys, quick shipping, good communication)

This link shows the package:

http://www.rallylights.com/detail.aspx?ID=350

This link is for the kit of two lamps and bulbs:

http://www.rallylights.com/detail.aspx?ID=739

This link shows a comparison between the E-code and the DOT vision plus that Rouge mentioned in his post.

http://72.215.196.56/hummers/headlig...visionplus.htm

TR

[TR65]

62 Short,

The problem is that without relays all the current for the headlights has to pass through the headlight switch. It is not made to carry the current of the bulbs we like to run nowadays (11 amps on high beam for me). With the relays the headlight switch carries only 100 milliamps to operate the relays. The relays are good for 30 amps each. The stock wiring is a little small for the high amp modern bulbs as well so it is good to upgrade the wire size while you are at it.

TR

[62 short step]

Originally Posted by TR65

62 Short,

The problem is that without relays all the current for the headlights has to pass through the headlight switch. It is not made to carry the current of the bulbs we like to run nowadays (11 amps on high beam for me). With the relays the headlight switch carries only 100 milliamps to operate the relays. The relays are good for 30 amps each. The stock wiring is a little small for the high amp modern bulbs as well so it is good to upgrade the wire size while you are at it.

TR

I have an aftermarket wiring harness, so if I upgrade to those newer headlights I will have to run relays correct?

[TR65]

I have an aftermarket wiring harness, so if I upgrade to those newer headlights I will have to run relays correct?

No, you don't have to. Headlight switch might not hold up though. But the one I replaced was 45 years old so a new one might last a long time. The relays are just a better solution. All modern trucks and cars use relays on the headlights.

TR

[markeb01]

Thanks for the input TR, I'll be checking those guys out.

Originally Posted by 62 short step

I have an aftermarket wiring harness, so if I upgrade to those newer headlights I will have to run relays correct?

The truth is all of these old trucks should be upgraded to relays even if the bulbs remain stock. There are a number of threads on the web discussing the voltage drop at the headlights with an original 1960 era wiring harness, and something less than 12 volts typically reaches the bulbs after traveling through all the undersized wire, the dimmer switch, and the headlight switch. With relays, full battery voltage (somewhere around 13.5 volts) goes directly from the battery through the relays to the lamps. The dimmer switch and headlight switch merely turn the relays on and off.

Even if a full 12 volts arrives at the bulbs versus 13.5 volts, that's a 12% reduction in power, and a noticeable drop in light output. Also with relays, the lamps no longer dim and brighten with engine speed, since they are receiving full battery voltage all the time. It's an easy upgrade with minimum investment and is really worth the effort.

[62 short step]

Thanks guys! I understand completely, sounds like an easy project for a saturday morning!

[ChevySixty6]

Thanks guys! I understand completely, sounds like an easy project for a saturday morning!

I'm sure if i started it on sat. morn, I might be finishing sunday night. It always seems like a 2 hour project turns into a 2 day one.

[TR65]

ChevySixty6 Re: One More Headlight Relay Thread

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Thanks guys! I understand completely, sounds like an easy project for a saturday morning!I'm sure if i started it on sat. morn, I might be finishing sunday night. It always seems like a 2 hour project turns into a 2 day one.

It is called the pi rule. Projects always take 3.14 times longer than predicted.

TR

[TR65]

Men,

I have been running the Hella E-Code lamps with H4 Hella bulbs for several months now. They are very very good. Much better than the sealed beam Halogens I had before.

I have two cars with Xenon's and they are better but the E-Codes are in the hunt.

TR

[rustyrodknocker]

This looks good . especially the kit that includes the relays. My only question is the fuse. Do you really need one to protect the relays? Are late model cars wired this way? If that 20 amp fuse pops you need a photgraghic memory on a country road. Ive been there. Its a very bad expierience and it takes a while to get your trust back and your families if they are in the car. It happened to me twice in a dodge that stopped regulating voltage, popped both headlights a once. the second time I knew to stomp the dimmer switch. with this diagram if its light out you have no backup.

[rideblue00]

Suscribed ! thanks

[TR65]

Rusty,

Good point. You could easily use separate fuses for high and low beam. My fuse box sits on the inner fender and I keep a bag of fuses in the cab.

I believe in fuses. If one of the power wires shorts out it could make a mess out of the wiring, or worse.

I actually have the lights double fused. Some big fuses on the left of the fuse box in the picture control different sections of the wiring. (Lots of wiring with an LS motor). The original truck wiring is run off one of the big circuits.

TR

[FreakyMalo]

Great write-up!

I built a similar relay system with Bosch relays for my '60 Olds and it made my lights brighter without changing out the bulbs. I did the same as you with heavier wire and good grounds. It takes the load off the headlight and dimmer switches and you don't get the voltage drop from the switch to the lights.
One trick I pulled on mine was putting a diode between the high and low beam input wires. With the flow going towards the low beam side. This will make the low beams stay on when you hit the high beams. Really nice when you have quad lights.

[TR65]

Good tip Freaky.

(The diode would connect the light green and tan wires in my diagram, would need to be rated at a few hundred milliamps.)

Thanks,

TR

[Shooters_7]

Will an American Autowire complete wiring harness have this update or will it be something that I still have to add?

[TR65]

Shooters,

I don't know for sure but just looking at their web site it doesn't look like they include headlight relays or wiring.

TR

[chevyrestoguy]

Outstanding write-up, TR!

Love the pictures with captions and your schematic. I am a huge fan of H-4s, and have used them for years. They are definately a "must-have" upgrade for any old vehicle.

[Alan's Classic]

Thanks for the write up and inspiration. I used it when I did mine.