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Ford headlight wiring upgraded

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sdiesel
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Ford headlight wiring upgraded

Post #1 by sdiesel » Sun Mar 22, 2020 11:33 am

A common oversight of Ford. Who ever designs these things anyway? And why did they wait so long to fix it?

To bypass the power going thru switch and replace with relays.
Commonly done, but when you do it, do u wire to keep high and low beams on simultaneously?
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

pmuller9
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Re: Ford headlight wiring upgraded

Post #2 by pmuller9 » Sun Mar 22, 2020 12:04 pm

No. You wire in a second SPDT relay that switches between the Low and High beams.

The power from the first relay goes to the Common terminal (30) of the second relay
The NC terminal (87A) goes to Low beams and the NO terminal (87) goes to the High beams.
The second relay is activated by the High beam switch.

It is important to note that the relay activation coil wiring should always be terminal (85) to ground or negative and the (86) terminal receives the positive activation signal.
The reason being some relays have a back inductance diode across the relay coil and will burn up if the polarity is wrong.
Last edited by pmuller9 on Sun Mar 22, 2020 12:28 pm, edited 3 times in total.

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bubba22349
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Re: Ford headlight wiring upgraded

Post #3 by bubba22349 » Sun Mar 22, 2020 12:20 pm

No of course not having both the high and low beams on all the time would be illegal. The first thing you need to do to insure good electrical performance, is do a good clean up of all your grounds and connections at each end.

As for the fix for dim headlights besides making sure all the wiring is in good condistion you can find the info in the below link for doing the excellent mod of using a pair of headlite relays. This provides full battery voltage to the headlites making them nice and bright and taking most all the load off your headlite switch so it lasts longer too. It's well worth the effort for safety on a car or truck that's driven often. Good luck :nod: :thumbup:

Example on installing a pair of Headlite Relays on an early Ford Mustang

http://forums.vintage-mustang.com/vinta ... hting.html
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: Ford headlight wiring upgraded

Post #4 by BigBlue94 » Sun Mar 22, 2020 6:42 pm

I used the kit available from BroncoGraveyard, along with an H4 conversion kit on my 85 bronco. Holy cow, the difference is night and day, literally. Its pretty much a plug n play ordeal with a pair of relays and the correct plugs for your model year.
1985 Bronco. 309ci I6, NP435, 4.56 gears, Detroit locker and tru-trac, 4" lift, and 37" swamper tires. The 309 is 9.75:1 CR with a Schneider 140H cam, 4bbl, roller rockers, larger valves, and headers.

sdiesel
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Re: Ford headlight wiring upgraded

Post #5 by sdiesel » Mon Mar 23, 2020 12:44 am

Thanks to all. Paul I will have to draw a pic to fully follow ur instructions.
I have built several of these , each time a little more refined and astute till finally I come crashing into the very same design that I thru blood and tears, had fitfully developed on my own turns out, was available fully developed from a number of suppliers.

But
My keenest interest is burning both filiments at same time high and low. For good measure I have powered a third relay to kick the big driving lights on 100 watt landing lights 5".
I'm fond of exciting the high beam relay from the low beam / headlight switch so it is NO when headlights are on.
Then converting my floor switch to a ground switch to ignite the high beams thru the grounding wire in HB relay.
Totally illegal and most likely totally hillbilly, but in the monotoness, dreary wastelands of the western US, where often I find myself at the dark end of the day, legal / illegal vs bright and brighter seem to be two different matters. where another vehicle may be an hour away.
America's loneliest highway, by the way , is far from that.
I have some trouble even using my high beams on that overcrowded lonely road especially between Fallon and Austin.
My vote is the road from Wells down into Ely, NOW, THAT IS LONELY ... I can use high beams for long looking stretches of highway and worry not one soul human jack rabbit or coyote. It is for this environment that 200 yards of pencil beam are so helpful to me
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

pmuller9
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Re: Ford headlight wiring upgraded

Post #6 by pmuller9 » Mon Mar 23, 2020 8:51 am

OK
What is your final decision?
1) Do you just want both high and low beam on at the same time always?
2) Start with just the low beam and when you turn on the high beam both high and low come on?
3) Either low beam or high beam but not both?

sdiesel
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Re: Ford headlight wiring upgraded

Post #7 by sdiesel » Mon Mar 23, 2020 9:49 am

My verbosity stripped bare it real question
I ponder is this
Using both low and high beam filiment through a single bulb should cause no problems with my lighting system ?
And have others wired theirs so both are brightly shining when high beams are engaged?
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

pmuller9
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Re: Ford headlight wiring upgraded

Post #8 by pmuller9 » Mon Mar 23, 2020 10:05 am

Since both low and high beams are drawing power directly from the battery by way of power relays they are isolated from the rest of the lighting system and will not cause a problem elsewhere. Just be sure to use at least a 14 ga wire to the headlights.

In this case it doesn't matter what others have done as far as low and high beam combinations.
It is a matter of what works best for you.

It sounds like you would like to have the low beams come on at first then low and high beam together for a high beam light.
Since automotive power relays have 1/4" quick connect terminals it would be easy to change lighting combinations on the road to see what works best.

You can always add a 800 million candlepower Short-arc Zenon seach light to the bed of the truck that overlooks the cab.

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Re: Ford headlight wiring upgraded

Post #9 by 68Flareside240 » Mon Mar 23, 2020 11:02 am

Learn something everyday. I always thought in a sealed round bulb, high beams were the lows and highs together. I have a 98 Tahoe that I did the low/high mod to on the composite lights. Used the highbeam feed to trigger a relay to send power to the low beams. Factory fog lights cut off with the high beams. From my (limited) understanding of Alabama law, this is not illegal. If the fogs remained on it would be. Regardless, if LEO stops you around here for that, they're just using it as probable cause to look for something else.
Last edited by 68Flareside240 on Thu Mar 26, 2020 11:27 am, edited 1 time in total.

pmuller9
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Re: Ford headlight wiring upgraded

Post #10 by pmuller9 » Mon Mar 23, 2020 12:00 pm

68Flareside240 wrote:Learn something everyday. I always thought in a sealed round bulb, high beams were the lows and highs together.

According to filament headlight bulb info when the high beam filament is on the low beam is off.
One reason stated for not having both filaments on is because of too much heat.
So this may be a problem with having a filament bulb with both low and high beams on at the same time.

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Re: Ford headlight wiring upgraded

Post #11 by guhfluh » Mon Mar 23, 2020 6:37 pm

pmuller9 wrote:
68Flareside240 wrote:Learn something everyday. I always thought in a sealed round bulb, high beams were the lows and highs together.

According to filament headlight bulb info when the high beam filament is on the low beam is off.
One reason stated for not having both filaments on is because of too much heat.
So this may be a problem with having a filament bulb with both low and high beams on at the same time.

Yes, it is too much heat in my experience. I have not tried with sealed beam bulbs, but have with 9006/9007/9004 styles. Housings melted and noticed when they started smoking. You may also have problems with the connector melting, depending on its composition - some are plastic, some are ceramic. The last thing is the wiring and connectors themselves. The ground path at the bulb is shared by both circuits and will have to carry the load of both circuits at the same time vs individually as stock and will also overheat and melt or catch fire easily.
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Re: Ford headlight wiring upgraded

Post #12 by sdiesel » Mon Mar 23, 2020 11:31 pm

800 million!!!! Gimme two! I dunno what 16hundred million is in the right way to say it , but that's a lot.

Legalities are puzzling because we are not changing what is DOT mandated, just the sequence.
My low beams work like Ditch lights on a train and high for , well high beam.
With my little 5inchers shooting a pencil beam out under the headlights.
Heat.on the 88 the flat dishpan style( if u could call it style) are plastic and prone to melting.
I have bored holes of one inch at the 6 o'clock position .
That helps but a hole on top would help with cross flow maybe 3 and 9 o'clock position.
My gripe with Ford one of a dozen is the flaky reflector material
Most recently I rigged up round lights in the space, looks ok. And is sooo much brighter
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

sdiesel
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Re: Ford headlight wiring upgraded

Post #13 by sdiesel » Thu Mar 26, 2020 11:43 pm

Question.
On my latest headlight wiring project, which I'm working on , I'm using duplex wiring 10 g which is way too heavy but is what I have . going out retailing right now is a bit risky. And I'm stranded in South Cali too where there is a lot of stuff going around

Anyway my ceramic plugs are 14ga.
the crossover wire 10ga duplex grey jacket.

I'm powering everything off of 2 relays this time, and am using 16ga fusible links, from power source to relay.
Can

Can I use 30 amp circuit breakers instead? Would that be a better or safer power Trip?

Unrelated question;
Also with my 3g alternator, I wired direct to battery positive with , if I remember rightly, a 100 amp fuse. Should I have a diode somewhere to prevent power from going back through alternator?

Also also, whenever if ever I get back to shop the battery will be relocated under the flatbed behind the cab.
I gonna try the newer starter too at this time.
Can i run my alt feed thru a fuse directly to starter with a flag terminal, and then on to the battery using that power feed solely?
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

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Re: Ford headlight wiring upgraded

Post #14 by pmuller9 » Fri Mar 27, 2020 8:03 am

Use a 30 amp "Trip and Hold' breaker for the head light system.
This way you can trouble shoot a problem and not be stranded without lights after you fix it.

A diode or resistor in the Lt grn/red wire ("I" terminal) is only needed if you are wiring directly to the ignition switch and bypassing the Alternator warning lamp or gauge.
This prevents the alternator from supplying power to the ignition system after you turn the ignition key off otherwise the engine will continue to run.

sdiesel wrote:Also also, whenever if ever I get back to shop the battery will be relocated under the flatbed behind the cab.
I gonna try the newer starter too at this time.
Can i run my alt feed thru a fuse directly to starter with a flag terminal, and then on to the battery using that power feed solely?


Yes if the starter has the starter solenoid.
No if you are using the remote Ford starter solenoid in which case the alt feed will need to go to the battery side of the solenoid.

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Re: Ford headlight wiring upgraded

Post #15 by sdiesel » Fri Mar 27, 2020 9:37 am

Ok thank u for this.
Effectively then with the trip and hold I can use one for both headlights.
But where?
I'm guessing between relay and light harness where I currently employ fusible links, not between the " trigger wire" coming from my light switch to the relay via the factory Ford harness.
Right?
Not sure.i need to have a way to cut power to the circuit breaker if it trips, to reset it.....
I'm in over my little noggin here

I'm awake now, I think I figured it out circuit breaker replaces the fusible links , as my trigger wire cuts power to the system on the other side of the system relays
Last edited by sdiesel on Fri Mar 27, 2020 10:08 am, edited 1 time in total.
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

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Re: Ford headlight wiring upgraded

Post #16 by guhfluh » Fri Mar 27, 2020 9:41 am

I agree, breakers can be nice to have in automotive applications, but not the self resetting kind.

Even if you have a PMGR starter, it is not recommended to wire through it from the alternator because of wire resistance, wanted battery capacitance and charge/voltage sense differences. I really dont see it being an issue though with the wire gauge being large enough.

The normal 3g alt is also a 130A unit and from memory the fuse 150A. If you have the smaller 3g alt, 100A sounds right for the fuse, but you may want to upsize things if you have the larger unit and plan on more accessories. If you only have a single v-belt drive it may be the limiting factor anyway before you blow a 100A.

P.S. Yes, in place of the fusible links, not in the trigger wire from the headlight switch(it should have a breaker in it factory anyway). You shouldn't need to remove incoming power to reset the breaker when needed, only fix the short :)
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Re: Ford headlight wiring upgraded

Post #17 by pmuller9 » Fri Mar 27, 2020 1:21 pm

The Yellow/White ("A" terminal) from the alternator is the sense line.
The alternator will maintain regulated voltage at whatever point you connect that wire to.
It is best if that wire connects to the same place that you are pulling power for the rest of the truck.

Example:
Lets say the alternator regulator is set for 14.2 volts.
If you are making power connections for the headlight system and the rest of the electrical system at the battery cable side of the starter solenoid, if the sense line also connects at that point the alternator will try to maintain 14.2 volts there and both the battery and the electrical system will see max voltage.
If you connect the sense line at the alternator output, it will be at 14.2 volts but the rest of the system will see 14.2 volts minus any voltage drop from the supply line from the alternator to the power pickup point at the starter solenoid.

The voltage drop will be determined by the gauge and length of the wire and the amount of current running through it.
There can be a considerable drop when running at night with headlights, fog lights and a rack of overhead lights.
If for some reason the battery was low and is having to be heavily charged that will add to the drop.

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Re: Ford headlight wiring upgraded

Post #18 by sdiesel » Fri Mar 27, 2020 11:39 pm

So yellow white to positivepost asking as the alternator charge wireis not connected at the same post
Or the positive side of the fender relay and alt charge wire at battery??
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

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Re: Ford headlight wiring upgraded

Post #19 by pmuller9 » Sat Mar 28, 2020 12:49 am

Where are you connecting the alternator charge wire to? It should be at least a 6 gauge wire.
Where are you taking power to run the headlights and the truck electrical system from?

Normally those connections are made at the battery side of the fender starter relay.
If so then the yellow/white sense line also connects to that same point.

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Re: Ford headlight wiring upgraded

Post #20 by MechRick » Sat Mar 28, 2020 11:21 am

If you have 10 gauge wire in surplus, just run two of those from the alternator to battery +. That's what Ford did on many factory vehicles, and what I did on my Bronco.

I didn't fuse mine (probably not the best idea). I did make absolutely sure there were no sharp edges or possible short-causing situations. My run is about 3 1/2 feet.

Paul is spot on about the sense wire. Any resistance in the B+ wire adds to the charging voltage output, which on Ford's is a bit high to begin with. Much over 14.5v will shorten battery life, especially in the hot Southwest.

I feel your pain with the headlamps on the bricknose trucks. Of the three obs-style, their lights seem to be the worst. I like the rectangular halogens better...
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Re: Ford headlight wiring upgraded

Post #21 by sdiesel » Sat Mar 28, 2020 12:00 pm

I've done this in different ways. Sometimes 4ga. Or duplex wire at 10ga works and is tidy.
A number of Japanese makers whom I admire , specifically Mitsubishi use two charge wires to the battery from the alt. In 12ga.
I used 10ga in duplex grey , cause it was handy.
I believe I have 150 or 100 amp flat super fuse laying on top of the battery that connects wire to battery. Mega fuse whatever it's named.
Seems to work.
Yes my yellow white is to the fender relay.

I told by old hands in The shop to avoid connecting this wire to the same location as the charge wire(s) to avoid a feedback situation like Paul discussed above where the alt is just reading its own charge not the actual consumption/ use .

Ok I go with that, measure consumption rather than supply.
I've got long hours of doing nothing here in pauma valley CA. Confined to quarters essentially though I can move about , I am reluctant to go Anywhere, so I rebuild my headlight harness again refining it more, but I have to say 10 ga. Duplex wire is a little heavy for headlights.
But again it's what was in the wire pile.
So I might mail order some 14 ga duplex and start over.
Bored fun
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a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

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