A couple years ago, I thought the headlights in the yellow truck dim, so I bought some nice new Sylvania lamps for the truck. Didn't make a difference, but at least I had new headlights!

Anyway, last fall I experienced several occasions where the headlights would simply go dark. There didn't seem to be any rhyme or reason to the timing, just a random thing. It was suggested that I look at the headlight switch, the dimmer switch, the grounds and the hots. A cursory inspection didn't reveal any problems, and the problem went away. As I said, it was random, and I rarely drive the yellow truck at night anyway.

Well Christmas rolled around, and I was buying myself presents. In addition to the nerf bars for the brown truck, I bought a relay style headlight harness from LMC. I didn't install it right away, because I was being lazy and gave myself other priorities. After working my way down the priority list, today was the day to install the harness.

I had also been putting this task off, as it seemed like it'd be a PITA to track down the headlight wires through the fenders, but it wasn't. The entire job was, as my grandson says, "easy as pie":




LMC care package: harness and dielectric grease



Harness rolled out so I could see it



Drivers side headlight connector and ground lead



Headlight plug and socket



Relays



Hot leads



Always use dielectric grease on electrical connectors



Remove the two screws holding in the outer bezel



Remove the four screws for the retainer



Don't let the lamp fall out



Factory socket...wires seem a bit...weak



Socket...a bit of corrosion



Ewww...no wonder the lamps are dim



Grounding the new socket



Better clean these contacts...



Much better!



Dielectric grease (hint:easier to put the grease in the sockets)



New socket on lamp



Replace the lamp



Retainer



First relay mounted to radiator support



Both relays



Dielectric grease in relay sockets



Relays hooked up



Wires run through hole in hole in radiator support and through corner of battery tray



Wide shot of relays behind horn



Grease on slightly corroded connectors



Connecting the new harness to the old



More grease in socket



Replace headlamp



Leads to hot side of starter solenoid. Instructions say direct to battery, but I like this better



Quick release connector



Wide shot of wires in relation to battery



Low beams



High beams

Total installation time was two hours. That included being super careful, spending a lot of time obsessing over where to run the harness, gathering tools, taking pictures and cleaning up.

Even in the daylight, without the engine runnimg, I can tell the headlights are already a lot brighter. I'd say this is an upgrade that anybody on this forum could handle, and if I might be so bold, given the safety of better headlamps, everybody here SHOULD do

Anyway, the kit is well worth the $30. Especially since it comes with the plug and sockets-nothing to cut or splice. And if it does fail, just plug the original back in-its all still there!

 

Nice write up!! Fine work as always!

One question: Are the hot leads you ran off of the + side of the starter solenoid equipped with an inline fuse??? Can't tell from the pictures. If they are not fused, I'd feel a lot better if there was a fuse in that line, as close to the solenoid as possible.

 

I knew I left something out of the write-up...

The hot leads from battery to the disconnect are 30 amp fusible link wire

 

Excellent write-up and pics - thanks for taking the time ! I had a headlight go yellow one time last year, hasn't been a problem since but I suspect it was wiring related. I've added this to my project list!

 

Its a nice upgrade my 79s lights are better than alot of 90s stock cars because of this upgrade. Well worth the cost of the kit with stock ford headlights.

 

They make a similar harness 2 relays direct off Battery power (fused) that has a diod that lets you have BOTH high and low on when you are on high beam...diod can be unplugged if you do not want that option.

Plugs in to the passenger side headlight OEM harness then you get 2 new plugs, one for each side. Good to use if you go H4 upgrade bulbs.

Yes it is for a EB,but I am sure they have them for 73-79 trucks??

https://www.tomsbroncoparts.com/prod...ord-bronco-new

 

it's amazing how marginal the original harnesses are, and the resistance can cause heating and failure in the switch...relaying saves your switch from carrying all that current, along with the performance boost....$30 for a simple kit, i'm probably in, but i have wired from scratch with bosch relays, heavy-guage wire to batt./alt., and 30a. breaker...the 7" rounds put out a lot of light regardless, so i don't think i'd want the low beam coming on along w/ hi...then again the LED's are coming on really strong and don't need hardly any power

 

I can also recommend this upgrade. With the relay kit and 7" round Halogen upgrade bulbs from LMC my Dent lights work better then a new DD with HID.

I did customize my wire routing and used breakers instead of fusible link so a little more than 2 hours install for me... but not much.

 

Just did this upgrade on my '66 f250 4x4. Headlights were good before, GREAT now. Took me less than an hour all told, and you can hardly tell the harness is installed. Super quick super easy.

 

For those that have not done the relay thing yet (but you all should!) a quick temporary "fix" for the headlights going out is to unplug one headlight.
If the lights simply go dead at random from the thermal circuit breaker in the headlight switch overloading, reducing the load by roughly half (not accounting for different resistance values from left to right after all these years) then it should get you home at least.

This all usually happens awhile after a headlight upgraded. Everything worked fine if you had the old weak 45 watt low beams, but for some reason adding a measly 10 extra watts to the modern 55 watt legal limit seems to put them over the edge.
If you're like me and loved playing with the high-beams after the first switch to H4 bulbs, your circuit breaker might start flipping out sooner rather than later.

But definitely do the relays to these older trucks if you can.

Paul

 

Hey Papa Bear, I am currently working n this upgrade. How did you run the leads to the drivers side? Over the radiator? In front? Under the radiator?

Thanks.

 

The run across the front was barely long enough, so it’s run in front of the radiator, behind the grill, at roughly headlight level. I ran the lead into the hole near the battery tray mount, so I could mount the relays on the radiator support and still run the supply line to the starter solenoid

i can get some pics tomorrow if you like

 

I ran mine the same. I haven't buttoned everything up yet, but should finish tomorrow.

No pictures necessary unless you need an excuse to tinker on it.

 

One more question, did you leave the stock ground wires in place?

 

When I rewired my truck, I was able to get the relay at the local auto parts store. I also installed grounding bars at all light locations and ran 10ga wire from the battery through the ground bars.