Headlight Relays ARE Worth it! (If done right.)

Gerald Morris

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Greetings C-body Moparians,

Since the wiring is done on my headlight upgrade, I can start sharing my experience with folks. I'm happy to report this worked better than I expected, and if done well, this WILL significantly improve headlight luminosity and decrease the voltage drop imposed from running them.

1. Materials: This is the most decisive set of choices to make. Having examined a good number of pre-fab headlight relay conversion harnesses, I noticed that NONE of them use #10 AWG from power source all the way through to the headlight. Since any constriction in ampacity limits the entire circuit, this MUST BE AVOIDED if good cost effect is the goal. It is with me, always.

So I made my own harness, exclusively with good U.S.A. made #10 AWG primary wire, finely stranded for audio power which I bought from an eBay vendor. This really is the BEST #10 stranded I've ever handled, in 35+ years since my electrician's apprenticeship. An auspicious beginning.... I chose red for high beams, black for low and white for ground, just as Chrysler (or FoMoCo, who actually made the original, 53 yr old harness.) did. Best to be consistent in wiring conventions when adding new circuit elements to an old system.
20181112_143104.jpg

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The original headlight connectors have become quite brittle with age, as I found when replacing a low beam bulb a couple years ago with a junkyard buy. Be this as it was, I opted to keep them and just plugged a couple male slide connectors into the driver side low beam connector, nearest the battery where my relays
20181112_142141.jpg

were to be placed. While the cheap sino-relay that came with my pusher-fan had a pre-fab harness wired
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with #14 AWG wire, I purchased GOOD TYCO-BOSCH relays, made in Portugal for this job. I could find
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NO relay connectors pre-wired in #10 gauge, which compelled me to just use 1/4 inch female slide
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connectors.

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The 4 circuit glass fuse holder from Dorman (Rock Auto purchase) worked perfectly for my design. I had already used two circuits for the cooler fan, leaving 2 spaces for the high and low beams. I use ONLY GLASS FUSES in Mathilda, and preferably Society of Fuse Engineers (SFE) certified ones.
20181112_150141.jpg

Again, I'm blessed with some acquired from a deceased old duffer who hoarded treasures like these. Pity modern plastic fuses aren't tested or designed with the same old school rigor these were.

I fed the power supply side of my 2 30A fuses with a bit of #8 AWG wire, again meant to power audio amps and very finely stranded for maximum conductivity, straight from the top post terminal on the battery to the fuseholder, using a split brass bolt "kerney" to attach 2 short pieces of #10 to the two spaces on the
20181112_155745.jpg

fuseholder and to the kerney. I use the same device for each of my two critical power connections, from

the alternator to the battery, then from battery to starter relay terminal post. The two 6 inch #12 AWG fusible links each attach to a kearney binding them to the #8 feeding the rest of the circuit. I might use a fusible link for the headlight feeds if I deem it likely that they might ever short. I HATE sacrificing ampacity for safety in such a setup, and the fuses DO protect everything below them. I might get a 10 gauge link instead if I lose sleep over this.

I have to stop this installment of my article here for now, having reached the limit on uploadable graphics. My server/workstation has also thrown an exception and needs a reboot.

To Be Continued.....
 

Fury440

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Why glass fuses, wouldn't you be better with self resetting breakers that will pulse the lights instead of leaving you blind? Will you post a circuit diagram, I'd like to see how you've tied into the factory harness.
When you crimp your terminals. force some grease into the wire end, multi strand wire with many small strands will wick moisture up into the wire and start corrosion.
Project is looking good.
 

Gerald Morris

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As promised:
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This will be wrapped first in 3M RUBBER tape, meant for high voltage and kerneys.
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Then wrapped in high grade 3M vinyl tape, to render it "electrically and mechanically secure. Before I tape ANYTHING though, I will torque down that split bolt WITH RIGOR!
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After taping the kerney, I have to run the new power leads to the headlights. Lacking insulated slide female connectors in 12-10 AWG, I use 2 layers of shrinkwrap to insulate these connections, as can be seen in the next pic:
20181112_161727.jpg


Time to make up the ceramic headlight sockets. Again, industry DOES NOT MAKE H4 headlight sockets with readymade #10 AWG pigtails; which is just as well. I perforce had to buy empty sockets with uninsulated slide connectors which had to be crimped/soldered onto the conductor after it was shoved through a silicone* (*TOUGH stuff too!) boot used to strengthen the ceramic socket. I purchased two 2-packs for ~$10 ea. "Quality costs" but this was the ONLY deal I could find that permitted me to use #10 from relay to headlight sans reduction in wire size.
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As can be seen below, they make a slick socket once assembled.
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They came only in the 3 slot low beam connection configuration, but 'twas easy enough to leave the black low beam conductor out of the high beam sockets. I used old fashioned red wire nuts to splice together the wires. By now folks should realize I dislike permanent wire connections in most contexts. I made a pretty lineman's splice soldered up for my alternator lead (connecting the output stud to the wire.) but aside from such rare cases, I want my wiring to come apart when I want it to, and stay together when I want that. To assure mechanical strength, I used cable ties to bind my joints tighter, relieving the wire nuts of tension to better keep the splice intact.
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Attend to how a 1/4-20 flanged nut secures two white grounds to a radiator mounting bolt. I use a brass machine screw over near the relays to secure a 10 gauge ground lead to the frame there. The passenger side pair of headlights likewise ground to my nice shiny aluminum radiator. This detail permits ample electron flow as much as the anodized slide connectors in the sockets and the #10 wire from the battery to the relays. Note the red tape on the kerney close by the fuse bank on the left. The supply side slide connectors on the fusebank all are double shrink-wrapped. You can see how I use the 1/4-20 nut-bolt combination in my "universal" terminals to attach ring connectors to the terminal. This gives good connection while securely holding the conductor in place. Shoving too many conductors into the space meant for the main conductor (#4 THHN ground, #2 for the starter) ruins the connection for ALL conductors in the clamp! Be advised you budget minded Moparians.
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End of Chapter 2.

Again, despite all my care with this job, I was ASTOUNDED with how much the luminosity of my crappy Sylvania halogen headlamps increased with this new harness AND how I recovered over 1 volt from the hideous drop when I turned the old circuit on.

This was a worthwhile investment.

Next, NOS GE and Westinghouse 400X headlights! (Hopefully by this Sunday.)
 

Gerald Morris

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Why glass fuses, wouldn't you be better with self resetting breakers that will pulse the lights instead of leaving you blind? Will you post a circuit diagram, I'd like to see how you've tied into the factory harness.
When you crimp your terminals. force some grease into the wire end, multi strand wire with many small strands will wick moisture up into the wire and start corrosion.
Project is looking good.

I WILL slather some dielectric grease onto all my bare conductors and the wire-nutted splices. I have plenty 30A SFE fuses, some in myt glove box or ash tray. If I have that bad a problem, I'd rather FIX IT than keep re-setting a breaker OR replacing fuses.

All I did to tie into the old harness was push a male slide-in connector into each slot on the driver side low beam socket. It's THAT EASY! Those control each relay. Red for HI-beam. Black for lo.
 

FURYGT

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Thanks for the detailed post. If it were me, I would have used Marine grade connectors and would have added shrink wrap over all of the connectors to help prevent corrosion.
 

67Monaco

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So when do we get to the done right part?

No offense but IMO pig tails have no place in a car.
 

Gerald Morris

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As mentioned in the post, I like my joints to be made for electrical and mechanical security AND ready disassembly, not aesthetics. Dielectric grease does very nicely for protecting exposed and otherwise vulnerable conductors, especially in joints. Brazed junctions such as the infamous one under the dash on the main conductor with an auxiliary leading down the driver side kick panel certainly LAST, but simply compel people to cut them apart, leaving one then with the issue of how to splice the new junction or to replace the entire wire. (I opted for the latter, eventually.) Adhering to outmoded technical standards simply out of reactionary predjudice suggests senility. I normally don't cotton to wire nuts either, but good ones do their job. I live in a 41 yr old trailer abounding in them for the 12 VDC junctions.

Rubber and cloth tape can be used, and indeed on the fused links I do. Likewise, terminal strips can be employed. This is a solution I like and may implement in time. Mind you, the issue of protecting the terminal surfaces from accidental contact arises. I had purchased a 1.75"x2"x3.5" plastic box initially for the relays and fusebank, but the relative added labor for dubious protection persuaded me to discard it, for the relay/fuse bank.

Thanks for the detailed post. If it were me, I would have used Marine grade connectors and would have added shrink wrap over all of the connectors to help prevent corrosion.

GOOD suggestion, for which I thank you.

I probably WILL go back and shrink wrap the exposed slide connectors. There are too many good reasons FOR doing it and none against except initial haste, which is hardly compelling. If I had marine grade connectors on hand, I likely would have used them, but in AZ there seldom is call for such. To wit, an expense I've avoided to date.
 
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67Monaco

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Sorry I mean you no offense. However, I'm going to stick with pigtails have no place in the automotive realm. If you're concerned about splices with connectors or soldered joints, run all new wire for the circuit and do it right. Plain and simple.

What you have now is a fire waiting to happen. Be it 2 years from now or 20, it's huge glaring point of failure.
 

Fury440

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I agree, marrette wire nuts do not belong in any application where vibration will be present. Constant vibration will potentially loosen the connection. Another factor, wire nuts come in many flavours, the good ones aren't cheap and the cheap ones are dangerous and should be banned. Good ones have a spring inside which acts liked a torque limiter to stop the user from twisting the wires to the breaking point. The cheap ones have zero protection. Cheap wire nuts are made from recycled materials and have different thermal characteristics, they shrink went cold and expand when hot. Shrinkage will crack the side of the nut and loosen the connection. Expansion also loosens the connection. Loose connections produce bad joints which generate heat and will eventually will start a fire. You can wrap all the tape and shrink wrap you want, a hot joint will treat the wrap as fuel. Note also, wire nuts are designed to be used for solid wire, stranded wire needs a side clamp type such as the monster copper kerney type of connection. However, the kerney is a heavy piece of hardware and needs lots of insulated wrap and it needs to be mechanically tied down to protect it from vibrations.

Returning to my question about fuses vs breakers. Picture this, you are driving a winding road at night, in the rain with zero traffic and no moon. All your lights are on and you are happily zooming along in your bubble of light. Now a wire bounces against a sharp edge and causes a momentary short circuit. Two scenarios, your fuse blows, all light is gone, your night vision is gone and you freak out trying to see and hoping the road stays straight long enough to get stopped. The other scenario, your breaker cycles letting you know there is a problem while giving you enough light to safely stop and get off the road safely. The breaker solution is actually built into your headlight switch but is defeated when you switch the load to relays. Pretty well all cars have used headlight breakers for years. Super modern cars use semiconductors as breaker/relays to control all external lighting. Anyhow, make very sure all your headlight wiring is well tied down and protected from damage due to road debris!

Don't read criticism into my remarks, I'm only concerned for your safety.
 

luigi164

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Now a wire bounces against a sharp edge and causes a momentary short circuit

I think that if this is going to happen, the wiring sucks already. When everything is ok the wiring should be secured and would not even be able to bounce against a sharp edge anyway...:poke:
 

cbarge

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Gerald,I will give you credit for your efforts in installing the relays and do your own wiring.
But there is a harness out there that I use and swear by.
Plug and play,no cutting or hacking. Plus no spaghetti mess under the hood.
Made by Putco and the only thing I add is black tape to cover the yellow.
Eliminates any flickering and dimming of headlights and gives full power to the bulbs and taking away any heavy loads from the foot switch and headlight switch.
Putco 230004HW Premium Automotive Lighting H4 100W Heavy Duty Wiring Harness and Relay
61lg%2BE3BKTL._SX466_.jpg
 

Gerald Morris

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I agree, marrette wire nuts do not belong in any application where vibration will be present. Constant vibration will potentially loosen the connection. Another factor, wire nuts come in many flavours, the good ones aren't cheap and the
....
stranded wire needs a side clamp type such as the monster copper kerney type of connection. However, the kerney is a heavy piece of hardware and needs lots of insulated wrap and it needs to be mechanically tied down to protect it from vibrations.

Returning to my question about fuses vs breakers. Picture this, you are driving a winding road at night, in the rain with zero traffic and no moon. All your lights are on and you are happily zooming along in your bubble of light. Now a wire bounces against a sharp edge and causes a momentary
....
Super modern cars use semiconductors as breaker/relays to control all external lighting. Anyhow, make very sure all your headlight wiring is well tied down and protected from damage due to road debris!

Don't read criticism into my remarks, I'm only concerned for your safety.

Points WELL taken and considered!

I can use slo-blow fuses, or just get a pair of 30A breakers. I HAD considered the scenario you've described, BELIEVE me, and am well aware of the presence of breakers in headlight circuitry going back over 5 decades. For that matter, there are breakers that fit the SFE form factor of the required ampacity such as the BUSSMANN CBF30. I just ordered a pair for good measure.

Look, I know wire nuts fairly well, having worked as an electrician for over 8 years nigh 30 yrs ago. MOST WIRE NUTS SUCK!!!! Trust me, I'm WELL aware of their mechanical limitations too. 3M makes the best, followed by Ideal. Be this as it may, I will use split bolts as soon as I can. I HAD a stock of them in my connectors/terminals cabinet, which got knocked down by several MADDENED BATTLING TOM-CATS that rolled, thrashed, spun, dug and scattered the dirt they SPILLED SEVERAL DRAWERS OF MY CONNECTORS INTO just about 10 days before I got free time for this project. The smaller kerneys I had purchased for THIS JOB were among the lost fittings. For now the wire nuts will do. I use cable ties and gaffers tape in addition to split plastic flex to sheath my wiring and secure it. I'll get another stock of the smaller kerneys, tape them up in rubber, then gaffers tape or cloth friction tape, just as the original FoMoCo harness was done 53 yrs ago. I still USE that harness for turn signals, braking, tail lights in general with high confidence. I run LEDs in all that so the power/current demand is slight.

My WORST SIN nobody has yet noticed: the #8 AWG feeding the fusebank! I simply MUST PROTECT THIS somehow! I HATE compromising the truly EXCELLENT conductivity I've achieved with this job; my headlights have more than doubled their output as a result of this configuration, but THAT IS A FIRE WAITING TO HAPPEN! I plan to try feeding it with a short length (3 inch) of #12 AWG fusible link wire from the battery terminal. If the slight increase in resistance doesn't compromise the current to the headlights noticeably, then I will call it "GOOD" and close this phase of the work after securing the other overcurrent protection to my liking, protecting all exposed conductors with dielectric grease AND putting the junctions on a SOUND MECHANICAL BASIS!

Your concern for my safety IS appreciated, and I will pray for you too. I have Little People to protect, which is why we bought Mathilda to start with. In the 40+ yrs I've been driving, I've actually lost headlights while driving about 5-6 times. Half of these incidents were on either Louisiana or Texas 2-lane roads, LATE, with me in a state toxicologists and insurance actuaries alike WONDER at. I really do have good night eyes and such, but my Guardian Angel(s) are the Best! Still, I DON'T care to gamble with the lives of my dependents, PERIOD! I thank you deeply on THEIR behalf.

Bless ALL of you Moparians.

Next Week, we will install the NOS 400X bulbs and properly aim them, then see the FINAL RESULT of my humble efforts here. I also have a steering gear box to install, but I'll essay that subject in its proper place.
 

CBODY67

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I first read of using relays to run normal headlights from Dr. Daniel Stern, about 20 years ago. Other than using a relay to run some of the stand-alone driving lights of that era. Oscar and Super Oscar?

When I was having some wiring connector issues on my '77 Camaro, doing re-terminations of the harness AND discovering the variations of quality materials in many of the headlight connectors too, I was unaware that those headlight harness terminals actually got WARM to the touch, when in continued use. Not hot, just moderately warm.

Personally, I always like OEM-level crimped connectors. Easy to take apart and easy to put back together, or even re-terminate if necessary. Just my experiences.

Thanks for the illustrated write-up!
CBODY67
 

Fury440

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Points WELL taken and considered!

I can use slo-blow fuses, or just get a pair of 30A breakers. I HAD considered the scenario you've described, BELIEVE me, and am well aware of the presence of breakers in headlight circuitry going back over 5 decades. For that matter, there are breakers that fit the SFE form factor of the required ampacity such as the BUSSMANN CBF30. I just ordered a pair for good measure.

Look, I know wire nuts fairly well, having worked as an electrician for over 8 years nigh 30 yrs ago. MOST WIRE NUTS SUCK!!!! Trust me, I'm WELL aware of their mechanical limitations too. 3M makes the best, followed by Ideal. Be this as it may, I will use split bolts as soon as I can. I HAD a stock of them in my connectors/terminals cabinet, which got knocked down by several MADDENED BATTLING TOM-CATS that rolled, thrashed, spun, dug and scattered the dirt they SPILLED SEVERAL DRAWERS OF MY CONNECTORS INTO just about 10 days before I got free time for this project. The smaller kerneys I had purchased for THIS JOB were among the lost fittings. For now the wire nuts will do. I use cable ties and gaffers tape in addition to split plastic flex to sheath my wiring and secure it. I'll get another stock of the smaller kerneys, tape them up in rubber, then gaffers tape or cloth friction tape, just as the original FoMoCo harness was done 53 yrs ago. I still USE that harness for turn signals, braking, tail lights in general with high confidence. I run LEDs in all that so the power/current demand is slight.

My WORST SIN nobody has yet noticed: the #8 AWG feeding the fusebank! I simply MUST PROTECT THIS somehow! I HATE compromising the truly EXCELLENT conductivity I've achieved with this job; my headlights have more than doubled their output as a result of this configuration, but THAT IS A FIRE WAITING TO HAPPEN! I plan to try feeding it with a short length (3 inch) of #12 AWG fusible link wire from the battery terminal. If the slight increase in resistance doesn't compromise the current to the headlights noticeably, then I will call it "GOOD" and close this phase of the work after securing the other overcurrent protection to my liking, protecting all exposed conductors with dielectric grease AND putting the junctions on a SOUND MECHANICAL BASIS!

Your concern for my safety IS appreciated, and I will pray for you too. I have Little People to protect, which is why we bought Mathilda to start with. In the 40+ yrs I've been driving, I've actually lost headlights while driving about 5-6 times. Half of these incidents were on either Louisiana or Texas 2-lane roads, LATE, with me in a state toxicologists and insurance actuaries alike WONDER at. I really do have good night eyes and such, but my Guardian Angel(s) are the Best! Still, I DON'T care to gamble with the lives of my dependents, PERIOD! I thank you deeply on THEIR behalf.

Bless ALL of you Moparians.

Next Week, we will install the NOS 400X bulbs and properly aim them, then see the FINAL RESULT of my humble efforts here. I also have a steering gear box to install, but I'll essay that subject in its proper place.

Just be safe and when your dependents are involved - be even more careful. Crap happens and when it does, its usually at the worst possible time, so its your responsibility to make sure it doesn't happen because of something you did or should have done.

Be safe!
 

CBODY67

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Haven't looked at a Chrysler wiring schematic lately, but isn't there a circuit breaker in the headlight switch (as GM uses), rather than a separate one in that base circuit? When the circuit breaker cools down, light work again, compared to a blown fuse where everything stops until the fuse if replaced.

CBODY67
 

Fury440

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Haven't looked at a Chrysler wiring schematic lately, but isn't there a circuit breaker in the headlight switch (as GM uses), rather than a separate one in that base circuit? When the circuit breaker cools down, light work again, compared to a blown fuse where everything stops until the fuse if replaced.

CBODY67
True, but it works in the factory wiring because the total current drawn by the headlights passes thru the switch. The purpose of the relay conversion is to remove that high current from both the switch and the bulkhead connector. As such the headlight switch only passes the minimal current required to close the relays.
 

mobileparts

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I never list them on any websites -- but I figure I might as well add on to your mention of head light relays ----
I have plenty of New Old Stock Head Light Relays -- Both single and Double -- and 6 volt & 12 volt !!!!!!!!!!
All very very U.S.A. made --- no Portugal, no China, from back in the day of QUALITY!!!!!!!!!!!!!!!!!!!!!!
 
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