Wiring in Relays Headlights???

Charging, starting, lighting, gauges, HVAC

Moderators: FORDification, Thunderfoot

Post Reply
javamanxxx
New Member
New Member
Posts: 6
Joined: Mon Sep 07, 2009 4:16 pm

Wiring in Relays Headlights???

Post by javamanxxx »

So I have a 1971 F-100, I have had it a very long time. Thinking about maybe wiring in relays to power the headlamps. I have done some Googling and reading and watched some vids on Youtube. My question..... Is this mod/upgrade worth the time and effort? Will my 7" Halogen lamps really be that much brighter and make you glad you did the work? Or look into the option of replacing current lamps with some high quality LED lamps and globes/lens?
RGB
New Member
New Member
Posts: 9
Joined: Tue Sep 01, 2020 2:36 pm

Re: Wiring in Relays Headlights???

Post by RGB »

For the replacement Halogen bulbs seems there is no need.

BUT, old cars seem to develop issues with the grounding AND in the "connection" along the path, i.e. high resistance.

Owning several identical cars... NONE THE SAME in operation though... provided a glimpse of issues.

In one car, the headlights were "weak". (most voltmeters have alligator leads available, perfect for the Ground, simplify debug!)
SO, I removed the headlight bulbs and checked voltage just on battery ~12.5 VDC.
(FYI, engine running, the alternator should be pumping 13.5 - 14.x volts).

1. Voltage 11.5V at bulb, normal as the copper wire resistance absorbs a little.
2. Put a bulb in the socket, voltage was 9.5 at bulb, ouch!
3. Hooked meter ground to battery -, + to bulb, 11.5... what? (1/2 volt drop on power side)
4. Hooked meter positive to battery +, - to bulb, 10.0... what? (2 volt drop on ground side)

Upon walking the ground connections back to battery and removing, cleaning, a putting some dielectric grease to prevent future issues.
Also did the same to the positive side.

Voila, almost 12V to bulb. HUGE, HUGE difference in the light, WOW! Cost zero to fix.

Usually all the issues are the connections, not the wire itself. Bolted connections should all be redone, clean up, re-bolt. Stainless washers are good.
javamanxxx
New Member
New Member
Posts: 6
Joined: Mon Sep 07, 2009 4:16 pm

Re: Wiring in Relays Headlights???

Post by javamanxxx »

Thanks for the reply man. Sounds like a great way to start. I will do all that and see how goes it. I don't do a lot of night driving but more light is better.
pcmdub
New Member
New Member
Posts: 66
Joined: Mon Sep 09, 2019 2:15 pm

Re: Wiring in Relays Headlights???

Post by pcmdub »

javamanxxx wrote:So I have a 1971 F-100, I have had it a very long time. Thinking about maybe wiring in relays to power the headlamps. I have done some Googling and reading and watched some vids on Youtube. My question..... Is this mod/upgrade worth the time and effort? Will my 7" Halogen lamps really be that much brighter and make you glad you did the work? Or look into the option of replacing current lamps with some high quality LED lamps and globes/lens?
Pretty easy to test if it will be worth it. Just grab a 12ga or larger pair of wires, run them direct to the battery and test it. The headlight bulb has a three pin connector that you can get from Amazon or the parts store.
User avatar
basketcase0302
100% FORDified!
100% FORDified!
Posts: 6805
Joined: Thu Jan 26, 2006 7:11 am
Location: Hawthorne, Florida

Re: Wiring in Relays Headlights???

Post by basketcase0302 »

It's one of the easiest and safest upgrades you'll do to your bump.
Fact that the #14 gauge headlight wiring was borderline sufficient size from the factory, (barely being able to handle the amp draw of the OEM bulbs).
The halogen bulbs pull way...too much power for the old wiring that has been taxed to it's limit the past 40 years.
You'll notice no less than a 40% improvement of your vision too. :wink:

Highly suggest to skip the kits sold and buy the parts separately though to get the best possible results, (this way you source your own relays/circuit breakers/new ceramic bulb sockets/new solder type terminal ends and stranded wiring. :thup:
Jeff
http://www.fordification.com/forum/view ... 22&t=46251
SOLD-71 F-350 dually flatbed, 302 / .030 over V-8 with a "baby"C-6, B & M truckshifter, Dana70/4.11 ratio, intermittent wipers, tilt steering, full LED lighting on the flat bed, and no stereo yet (this way I can hear the rattles to diagnose)! SOLD!
Many Ford bumps / one 76' EB / and several dents through the years.
A lot of "oddball" Ford parts collected from working on them for 34 years now!
2008 Ford Escape 4 x 4
tsherry
Preferred User
Preferred User
Posts: 487
Joined: Fri Dec 23, 2005 11:26 pm
Location: Washington, Spokane

Re: Wiring in Relays Headlights???

Post by tsherry »

I haven't done my '67 F250, but I've done two '66 Falcons, a '65 Econoline and several 90's Crown Victorias.

One of the best, least expensive upgrades I've ever done. I don't drive the '67 at night too much, (actually don't drive it much at all unfortunately) but it is on the list to do.

I wouldn't hesitate to upgrade.

(Halogen lights are excellent, too. All the cars have them).
too many Fords, no where near 'nuff time.

or, money.
Ohiotinkerer
Blue Oval Fanatic
Blue Oval Fanatic
Posts: 852
Joined: Wed Nov 09, 2016 5:49 pm
Location: Galion, Ohio

Re: Wiring in Relays Headlights???

Post by Ohiotinkerer »

It's definitely worth switching over - I also don't drive alot at night with mine but the difference is night and day...... literally. I bought a harness from Octane lighting that is plug and play with the relays wired in and ceramic sockets......takes the load off your old wiring which was the main reason I did it - my factory harness was completely stock and hasn't been cut on so I went with that and led turn signal bulbs to extend the life of it.........

https://www.octanelighting.com/
"Life is a garden - dig it"........... :thup:

1968 F100 2wd - Rangoon Red - 360 w/T18 - power steering and brakes
1997 Honda CBR 900RR
Post Reply