Hey all. Sorry to ask a question I know has been asked a lot but I'm confused and could use some guidance because of a fine detail. 74 F-100 here.

First, I was driving home the other night and the headlights went out about half way. Passed cops, was lucky and they didn't stop me, but I pulled over and they came back on. I read it's common in these trucks so I'm looking for a relay harness for the brighter and reliable lights. I found a few on Amazon, my preferred place to buy (I have the card) and was wondering if either of this will work?


I ask because I see it's a 'LED' conversion harness. I may switch to LED's but will it also work for my current halogens? Is there anything specific I need to pay attention for when shopping LED headlights? These work?
Thanks as always!

 

I bought the same kit, but I'm not using LEDs, just my current head lights. I'm using the kit to relieve load on the circuit breaker in the light switch. It uses the passenger side head light plug on the harness to pick which relay, high beam or low beam, gets used. Yes ... it has two connectors that fit standard three prong headlight seal beams, halogens too. You'll just tape up the connector that powered the driver side, and current to the head lights goes through the relays, and the headlight switch just activates the relays, a low current compared to head light loads.

 

@tbear853 Great to hear, thanks. Looking forward to brighter lights! Is there a 'best' guide for wiring in the harness that might suit that kit better than others?

 

It's all plug and play. You'll want to maybe put a little electric grease on the terminals, carefully route the harness across above the radiator, and I can't think of any actual wiring you'll do.

high amp loads like the actual power to operate the head lights. Stock as Ford did it was that power was directed to the head lights through the headlight switch. The head light switch has a circuit breaker that is intended to kick off if power draw is too great, but it resets unlike a fuse, so you don't suddenly loose all lighting, like at night at 60 mph.

The harness of this kit only uses the same feed to switch relays on / off, and the relays direct battery power to the head lights. The kit only needs the use of one original head light plug, so the other is taped up. You will likely need to drill two holes in the radiator support near the truck battery to mount the relays, they are pretty common relays. The kit even has a fuse holder and fuse in the wire that has an eye to attach at the battery positive terminal. The fuse is to protect the power lead from a short circuit that might happen in a wreck, or other accident, just like other fuses. Kit has zip ties, etc for install.

Sample instructions found online

• 1. Disconnect the battery for safety.
• 2. Unplug the headlight connectors from headlight bulbs.
• 3. Plug in the removed female headlight connector on the passenger side into the male connector of the new harness.
• 4. Plug the new headlight connectors onto the headlight bulbs. Route to drivers side first. Ground the black ground wire to the core support.
• 5. Mount relays in an appropriate location on the core support above the passenger headlight.
• 6. Route the red wires to a battery source.
• 7. The old driver’s side headlight connector will not be used, it can be taped up.
• 8. Reconnect battery.
• 9. Turn on headlight and check if they operate correctly.
• For best performance we recommend the use of dialectic grease on all electronic connectors

If you do much night driving, trips, you might get and carry a couple extra relays just to have.
When disconnecting & reconnecting the battery, I always do the negative terminal first when disconnecting, and last when reconnecting.

Was in 1980s / early 1990s ... I had put two new head lights in my '77 seeking better light as the OEMs had dimmed, I never looked close at the OEMs then as I recall, I just put the "Plus 25"s in. They were advertised as brighter, yet DOT approved. I had no light meter, but they seemed brighter, I was happy. Brighter usually requires more amps.
December 2013, after retiring from the state, I went to work at a part time job at Advance Auto, and by then I very seldom drove the '77 (especially at night) as I had other vehicles (newer, better gas mileage, etc). I had noticed the '77s head lights seemed dim but I figured was just because I'd gotten used to newer vehicles head lights. I pulled into the parking lot, predawn, and another employee was standing outside enjoying a smoke (?) and he busted out laughing. I asked what was funny. He said my head lights were lighting up the radiator more than the road. I never had looked so close at them, but I did then. Turned them back on, the whole front end lit up behind the head lights. Most all of the silver reflecting coating inside the head lights was in a pile of silver flakes laying in the sealed beam in the bottom and as much light was free to go out the back side of the sealed beams as out the front lenses.

I bought two new sealed beams that day, I forget exactly which ones, but were Sylvania Xtra Vision sealed beams. I put them in that afternoon and the next morning about same time, I drove the '77 to work. WOW! Bill was there waiting, grinning, asked me how was different. I told him "Where I felt like a blind man driving yesterday, I felt like I was setting the road and ditches on fire today." He said those others shouldn't pass inspection, and I said they wouldn't if checked but if an inspection mechanic just looked to see if they worked in daylight, they might slip through.

Bill took those two old head lights that had loose reflector material in them and hung them in his camper as ceiling lights. Said they worked great.

 

As far as LEDs go; do you drive in cold/icy weather? At night? Then don’t run LED head lights.

Unless you have direct experience with a good LED headlight, I wouldn’t trust Amazon Chinese cheap with something critical. There’s also the question of actual brightness on the road, not necessarily Lumens. I forget the correct terms, but a lot of LEDs appear bright in pictures, but the color spectrum isn’t as effective as DOT halogens.

Also remember that LEDs are known to draw less current and be more efficient, which means less heat. Have fun chipping ice off a plastic housing that doesn’t produce enough heat to thaw itself.

Ok, I’m gonna go be grumpy and old somewhere else now. Lol

 

Good points all. I hate .... well, might be better to say "strongly dislike" LED head lights. We have them on our Forester and with the increasing population running them, with all the reflecting signs, is rarer to be able to even use high beams as even the signs will blind one. A lot of why they seem so bright is the receptors in our eyes reacting to the less red, more nearer blue light in their light output too (why they look white). Blue light will rob you of night vision, red light does not.

On second thought, I do hate LED head lights, especially in head lights, driving lights, light bars on lifted pick ups meeting me at night. Before retiring, LEDs were starting to be seen as head lights ... and unless I was busy, if a driver failed to dim them when meeting or following me or other drivers at night, was a good stroke there. For the record, I was never a fan of blue emergency lighting / strobes / etc on our police cars either. Red was hugely better as it sent a message to drivers and did not inhibit my ability to see at a scene at 2AM. My dept switched in 1982 after some legislator got a bill through changing state law ... and I soon grew to hate the change.

 

A little off topic but same vein, I’ve been surprised how many guys/gals are carrying the “10000 lumen” flash lights with the spots on their rigs and everything else, and somehow manage to not go blind on night shift, much less on code at scene with the dome lights on too. Just gives me a headache.

For me hunting is when I have the most lights, but aside from side arm light, try to keep everything else below 100 lumen, preferably 10 when navigating trails in the dark.

I guess this is how we know we’re old. And speaking of loud pipes….

 

I ordered a less extreme pair and didn't go super cheap but I may just stick with the halogens anyway. I don't drive the truck at night very often and we live in a very dark, very light traffic spot so it shouldn't be an issue as far as brightness goes but I am sure I won't like them if they stand out too much by looks alone during the day.

Getting the upgraded harness with relays should help brightness a good bit anyway? If that's really the case, I may just return the LED's and not even fool with trying them out.

 

Thank you for that! I will literally use it tomorrow when I'm going through putting the harness in.

 

My suggestion is to see what you think one night with just the relay kit and your halogens .... before installing the LEDs.

 

I installed the relay harness on my 2 trucks and yes the halogen lamps were a bit brighter than before the install. However I did swap both out to LED headlights. They are at least for me much brighter than the halogen and throw the light further. I also did much research prior to purchasing. I did not buy the most expensive, but also not the cheapest. The first set I bought were terrible they had absolutely no definition to the beam. It was just scattered light. Which for driving it terrible. Which is what brought me to do some research. Then I bought a pair that "said they were" DOT approved and it is stamped on the lens for about $120 and about 6 months of driving and a huge improvement. But only time will tell on longevity. Quite a few things I read and other customer reviews and comparison videos gave me confidence in my choice. I do quite a bit of night commuting for work. I do have a backup light bar just in case.

 

That's good to hear! Could you point me to which ones you bought? If these don't work out, I might give them a try. While half my drive at night is through a small town with street lights, the other half is still pretty rural and not a lot so I figured I could benefit from the LED's. I like both perspectives, will definitely try them both.

I bought:

The reviews are pretty good over all, they look pretty sharp in the pics people posted on their classic cars and trucks. Also listed as DOT approved, but might be iffy. lol

 

That's pretty funny, those are the same ones i bought just not from Amazon (not a fan). I could have saved $20 a set. Like I said im about 6 months in with them and drive my truck 2-3 days a week to work, I have a newer car as well i split it up with. But so far they have been good and the beam pattern is good as well.

 

Just so you know im not just b.s.ing you.....lol....


This is the pair I replaced because the beam spread was terrible.

 

A '10000 lumen" flash light with spot never bothered me when I was the holder of same. That extra dome light didn't bother me either and I used it a lot, but not while driving. Tried a red bulb in it once on a midnight, then I realized some OLs had some red print that just went away, but then I was not lit up so well either. When we had all red emergency lights, they didn't bother night vision, but you learned to not look long at blue ones as the ability to see "out there" in the dark was gone for a spell. Blue strobes on the roof sucked in the rain, but red revolving or strobes were OK even in the rain. I've asked units to turn off the rear blues when I was following on a call, etc. when they could. Wrote a letter once, sent to HQ, Sgt. at garage was not happy, but they did start adding a switch just to allow deactivating a rear shelf light. Then someone else complained because they forgot to turn it back on at scene.
Oh yea, loud pipes ....