Headlights go off and on while in motion.

[Remisdad]

My wife and I recently got a 77 bronco. On our first trip out after dark the headlights would go off and on at random times for random amounts of time. I did notice that it seamed to go between high beam and low beam. We also have an issue with our turn signal not working. We know the switch is bad and the folks we bout it from are going to fix once the part is received. Could the issues be related or not? We are really new to this so any suggestions are greatly appreciated.

 

[70_Steve]

My wife and I recently got a 77 bronco. On our first trip out after dark the headlights would go off and on at random times for random amounts of time. I did notice that it seamed to go between high beam and low beam. We also have an issue with our turn signal not working. We know the switch is bad and the folks we bout it from are going to fix once the part is received. Could the issues be related or not? We are really new to this so any suggestions are greatly appreciated.

First off, welcome to CB.com and congrats on the new Bronco!

The headlight switch has a thermal circuit breaker built in. If there's an overcurrent, the breaker heats up, opens the circuit and your headlights go out. When it cools down it closes again and the headlights come back on. That thermal circuit breaker has been known to go bad and open with just the normal current from the headlights. The fix is to replace the headlight switch.

In addition to replacing the headlight switch, you may want to consider installing a headlight relay harness. The headlight relays install in the engine compartment and direct current from the battery directly to the headlights, without the resistance of the stock harness to and from the headlight switch. In addition to reducing the current through the headlight switch, since it's only energizing the relays now, having the power to the headlights come directly from the battery results in brighter headlights.

All that will only help if your headlights are going completely off. The dimmer switch, on the floor, is what switches power from low beam to high beam. It's just a single pole double throw switch. I haven't seen or read where they've gone bad and switched between high and low beam, but anything's possible...

 

[Remisdad]

Thank you very much. I will get to work.

 

[astark]

First, have ya a good breakfast

 

[astark]

Then

Disconnect the negative battery cable.

Remove the headlight switch control knob and shaft by reaching up behind the dash and pressing the knob release button located on the bottom of the switch, it's a little metal post. As you press, pull the knob and arm out from the switch past the two on positions to remove it.

Unscrew the chrome mounting bezel on the outside of the dash by turning counter clockwise, there is a slot in it that will allow you to put a screw driver into and bang on if necessary.

The whole switch will pull loose from behind and under the dash. Disconnect the big wire plug assembly from the switch, you may have to pry them apart with a screw driver, if so be gentle with it.

Now just plug in the new switch and follow these instructions kind of in reverse.

My knob arm was to long, because I was missing a spacer, so I had to shim it with a nut between the switch and inside of dash.

 

[Remisdad]

Wow man! You probably saved me a half a day and more than a few four letter words. Thanks for the play by play. Being so new to it all this is a great help. Many thanks.

 

[70_Steve]

You probably saved me a half a day and more than a few four letter words.

Find a safe place to save those four letter words. Owning a Bronco assures you will need them on more than one occasion!

 

[Rox Crusher]

I second the recommendation for adding the headlight relay harness.

http://www.wildhorses4x4.com/product/Illuminator_Headlight_Harness

 

[blubuckaroo]

We had an interesting ride home one night. The lights kept going off when I hit the brakes hard. Turned out to be a bad dimmer switch and we were able to jumper it out and get home.

 

[Remisdad]

I would describe our ride home more like scary. We were on 285 the major highway that circles all of Atlanta. I may have used up all my four letter words for the year on that ride. The old girl did get us home in one piece. I have forgiven her and apologized for all the blessings I gave her that night. With the help of all you fine people our relationship will continue.

 

[DirtDonk]

If it happens again (in any vehicle for that matter) before you have time to perform any of the above fixes, try unplugging one headlight. It's easy and will reduce the load on the switch by half.
Sometimes that's enough to cure it temporarily, sometimes not. But at least it's worth a shot.

The relays actually allowed me to keep the old problematic switch after my first experience with that. Still in there to this day. Now that it only carries a small fraction of the current it used to, it's not opening the circuit-breaker any more.
Not that a new switch is not a good idea of course, but that just lets you know how effective the relay upgrade is.

Thanks for the shout-out (link-out?) Rox. Here's our other offering as well:
http://www.wildhorses4x4.com/product/NightLighterHeadlightHarness
Both are nice pieces. The less expensive one merely leaves out the little jumper option that allows you to run both the high-beam and low-beam on at the same time.
Also, imported vs Made in the USA. Which is why I'm glad we offer both.

I can't find the link at the moment Remisdad, but we also have a YouTube video of the headlight R&R process that astark was good enough to provide the blow-by-blow for.

Paul

 

[Remisdad]

Thank you sir. I believe I will take all of your suggestions and install the new switch and the harness. I guess it's time to do some shopping. Funny thing. When I first joined this forum I got many welcomes and one "and let the spending begin". It didn't even take a week and I am breaking out the old debit card. It's cool though. My wife and I love that ride and plan on having for many moons. Thanks again for all the help.

 

[astark]

If you got one of these type set ups with 55/100 watt bulbs

http://www.dufftuff.com/H4_Composite_Headlight_Conversion_p/7205.htm

It would be like extra potatoes with your meatloaf ;D

 

[astark]

Oh, and one more thing Remisdad, enter this contest before July 24th

http://classicbroncos.com/forums/showthread.php?t=227437

 

[pabluni]

In case you haven't noticed, we love spending other people's money!;D

 

[Remisdad]

Well it works. My new harness is on the way. Im really greatfull for the help.

 

[DirtDonk]

In case you haven't noticed, we love spending other people's money!;D

Ain't that the truth!

Paul

 

[BroncoLuva]

Just in case, I also had the problem years back with my '77, but I couldn't turn the lights on. Turned out to be a defective high-beam foot switch that my mechanic buddy figured. FWIW.