1976 headlights, high-beams flashing on/off

[Rayhunt]

I drove my 1976 Bronco last night for a couple of hours. All of the lights worked fine until I turned the headlights to high-beam. After a minute or two, both headlights begin flashing off and on together every few seconds. The rest of the lights were unaffected. Switching back to low-beam, the headlights remain on. I have Wagner Halogen 2D1 headlights. The alternator gauge stays centered at 0, and other electrical equipment like the radio and heater fan don't seem to be affected. Any ideas (dimmer switch, wrong headlights, main light switch, etc.)? Thanks for your help.

 

[Broncobowsher]

Headlight switch circuit breaker getting weak and starting to trip. Can also happen if overloaded or a short.

Or you can ignore the aging and failing circuit breaker and add extra complexity in the name of brighter headlights and put relays in.

I would start with a new switch if the wiring is good.

 

[Rayhunt]

OK. Good information.
I replaced the headlight switch last year; not sure what brand. I will try another.
Thank you much!

 

[B RON CO]

Hi, the headlight switch is a common failure on older Fords. The headlight draw goes through the headlight switch. It was bad enough before halogen bulbs. Now your modern halogen bulbs draw more amps then ever. I updated my 66 Bronco and 66 Mustang with the Niteliter headlamp relay kit. Now only minimal current flows through the headlight switch to activate the relays. Good luck

 

[Apache Bronco]

Could also be the dimmer switch. Pretty scary when you press the switch for high beams and the headlights go off!

 

[Jaxgtc]

I went through something similar a couple of years ago. Replaced the switch, dimmer and voltage regulator - none worked. I did my best to try to trace down a short, but that is nearly impossible. Like Broncobowsher said, I spent the $30 and got a headlight relay and the problem has been solved ever since. Simple to install, it plugs into the current headlight socket, leads to the positive side of the battery and the wires are easily hidden in the grille and not visible. I used 3M two-sided tape and hid it in the upper lip of the inside of the grille. Everyone who owns an EB should make this upgrade. I think all the vendors sell them, check around for pricing. Here is what it looks like:

https://www.wildhorses4x4.com/product/Night-Lighter-Headlight-Harness/Bronco_Wiring_Harness

 

[Scoop]

I would do all of the above. New headlight switch, new dimmer and add the relay harness - if you upgrade the lights to H4's or other highbrow lights. The old system was not designed for electrical draw of the newer bulbs. Now if you go with LED headlights the harness is probably not needed as they do not draw that much power.

 

[sykanr0ng]

Also check the dimmer switch wiring and connectors, they sometimes wear, come loose or corrode.

 

[Skiddy]

I would do all of the above. New headlight switch, new dimmer and add the relay harness - if you upgrade the lights to H4's or other highbrow lights. The old system was not designed for electrical draw of the newer bulbs. Now if you go with LED headlights the harness is probably not needed as they do not draw that much power.

mine were doing the same blinking off and on and brights they would just go off. put in new h4's with the relay kit all bright now and no issues

 

[DirtDonk]

The new switch is probably worn out from being a "new switch" because new stuff is much crappier than the original stuff was. Very likely why yours is tripping after only a year.
But older wiring and bad dimmer switches do add a lot of resistance to the system, which can make the circuit breaker think it's being overloaded by a heavier load.

For giggles you can measure voltage at the headlight socket to see how much less is read at the socket than at the battery. Not "if" by the way, but just how much. If you're lucky you might find as little as a half a volt drop, but it could be as much as a 2 volt drop!
If you see much of a drop that might explain the switche's short life since it's replacement.

If this ever happens on the low beams and you're away from home, you can unplug one lamp temporarily and drive home on a single headlamp. Not the optimal way to drive, but will often get you home without the lights going off completely. Been there!

But no matter what is going on, the relay upgrade is totally worth it. Especially now that you can buy kits for almost as little as it costs you to make your own!
We sell our "Nightlighter" version for $35 bucks. You can probably still buy the components for a little less than that. But not much I wouldn't think.

Good luck.

Paul

 

[taipeichris]

Hi Guys,

Stop!

Before you change the switch and start buying stuff, reach up under and behind the dash and slowly push each wire into the back of the plug for the headlight switch. These can be lose or could have been tugged on the last time you changed the switch.

NEXT.

Look at the high beam switch on the floor. There are two pressed dimples on the housing that holds it all together. This can also come lose. Unplug it, unscrew it and make sure the plastic insert of the switch inners is pushed all the way in. Click it by hand a few times and you will see the insert move in and out. This happened to me years ago and I just used a metal zip tie to wrap over the housing and keep that switch together. If it looks like it's lose, use a small metal punch and tighten that sucker up.

Good luck!


PS NOW GO BUY a set of fog lights or a LED bar to run as a back up for when this happens.

Twice it's happened to me, years ago once on PCH north of Monterey in the fog and rain on the way to SF and recently in the middle of the night on the 405 freeway going 80mph. NOT COOL.

Aren't classic cars fun?

 

[Rayhunt]

Wow! This is a great forum. So many extremely helpful replies.
I will jump into the troubleshooting and see if I can identify the problem. If not, good to know that there are other affordable and proven options to upgrade with newer technology.
Thanks so much to everyone who replied, and to ClassicBroncos.com for making it possible.

 

[gr8scott]

Could also be the dimmer switch. Pretty scary when you press the switch for high beams and the headlights go off!

Also check the dimmer switch wiring and connectors, they sometimes wear, come loose or corrode.

Or completely fall apart! Happened one night going home after the stock car races...lucky for me I carry jumper wires.

 

[sprint289]

Mine was the voltage regulator, also my volt gauge on dash was jumping around, regulator corrected both problems

 

[Pa PITT]

I seem to always get Snake Bit ... MAYBE THAT'S WHY MY BRONCOS name is Snake Bite.
I've got an after market wiring harness & I've got the added head lamp wiring harness.. My Head lamp switches last about a year. & My Dimmer switch defiantly has to be swapped out each year. & Yes I do have H6024 HEADLIGHTS.
......... I DO HAVE BETTER LIGHTS THAN I HAD BACK IN THE STOCK DAYS. But I can't believe I still have to change out my DIMMER Switch.
.... I've thought about building myself a HEAVY DUTY HARNESS. build myself one made out of maybe 10ga wire. & A 50 amp Maxie fuze. Like Tim the TOOL MAN .. ''MOORE POWER''.

 

[WheelHorse]

I can't say enough good by swapping out the lights and adding the new additional relay harness for both low and high beams. It's as good as a new car now.

 

[Rayhunt]

Problem solved - wire connection at the headlight switch.
I reached under the dash and moved the wires around a little and noticed that this would cause the headlights to flicker. So, I removed the headlight switch, disconnected the wiring plug, pushed all of the wires firmly into the connector and reinstalled the connector and switch. There must have been a loose wire, because the headlights have been working fine on high beam all week.

 

[DirtDonk]

Great news! thanks for the update.

paul