Headlights Stop Working

[willtel]

I've got a Painless harness in my Bronco and I'm using Hella H4 bulbs that are 60W/55W high/low beam. Sometimes when I drive at night the headlights will just stop working. I assume I and pulling too much current through the wiring since I don't have external relays on the headlight circuits. I am planning to add relays to fix the issue since losing headlights kind of sucks.

My question is what exactly is happening when my headlights stop working and why do they start working again a few minutes later? It seems like I should blow a fuse but that isn't the case since they come back on at some point.

 

[75MIKE]

The thermal breaker in the headlight switch gets hot from too much load and trips out. Has few seconds or minutes to cool off. Thermal breaker re-sets lights come on. Repeat.

 

[1971lubr]

Add a Wildhorses illuminator harness, problem solved.

 

[75MIKE]

Add a Wildhorses illuminator harness, problem solved.

Yes, very nice harness,that's what I installed. I did have to add an extra ground wire in the harness and bring it back to negative post on the battery. Depending on the 50 year old spot welds for a good ground did not work out very well.

 

[KyleQ]

The harness is a piece of cake to make if you have the materials laying around - I added relays for my high beams and low beams, excellent performance increase.

 

[mattyq17]

Kyle, what do you need to make the harness?

 

[DirtDonk]

Two standard "Bosch type" cube relays (one for high beam, one for low), some wire, a few connectors, a couple of 3-wire headlight connectors, and either a couple of fuse holders or those little circuit breaker thingies.

Not that hard, but it depends on your time and whether fun is worth a few bucks. It's very satisfying to do yourself, but also not a bad deal at $35 bucks (https://www.wildhorses4x4.com/product/Night-Lighter-Headlight-Harness/performance_lighting_78yr) if you just want it done.

As said, make sure you ground it well, and that your body is grounded well in general. Most are not, so adding a few extras is good practice even if you were not messing with the lights.

And speaking of which... If this happens again before you get the relays done, unplug one headlamp from the back. This halves the load on the switch and should get you home with no more drama.

And speaking of the switch... Frankly, your Painless harness and switch (presumably a new switch too?) should not be doing this no matter what.
Yes, you still benefit from the better design by using relays, but the new harness should be more than adequate for running around with your high-beams on all the time.
Perhaps you got a bad switch. That would not be out of the ordinary these days, as practically every brand of switching product out there today is capable of being bad right out of the box. If yours is new then, this may be the reason.
Or in your case, not actually "bad" literally, but just born with an over-sensitive internal circuit breaker.

The new relays will allow you to leave the switch in place most likely, since 90% or more of the load is now on the relays and not the switch.

Good luck.

Paul

 

[KyleQ]

Yeah - that kit is nice but with shipping I'm betting you are close to the $50 range. Everyone who uses their headlights for any night driving should be using those - I'm not just talking Broncos either, it makes a difference on any older vehicle.

 

[SteveL]

Before you go too crazy check the hi-beam switch on the floor. I run the Hellas with a centech harness with no problem without relays or anything. When I had your problem the floor switch was cracked where the harness plugs in.

 

[DirtDonk]

Good call Steve. Those pesky switches are always failing. They're not exactly in a switch-friendly location, and the new stuff is prone to failure much quicker than the old ones were anyway.

But here again, was that switch replaced as part of your Painless install willtell?
If so, while it should not be bad already, you just never know. Well worth the few minutes it takes to check.

Paul

 

[willtel]

When I bought my Painless harness I didn't get it with replacement switches. My factory switches all worked ok so I saved a little money by reusing them.

My high beam selector switch is new. My floorpan bent a little from having the parking brake too tight and cracked my old one so I had to replace it.

I think I will make my own relay harness using these instructions.
https://www.danielsternlighting.com/tech/relays/relays.html

 

[SteveL]

My centech came with a new switch but like Paul said the new ones are cheap. I must've kicked it or something. I the napa had a better one with less plastic.