I have posted before about this but I still have had no luck. I even took the switch socket apart at tightened all the lose connections. This is a new switch. With the old switch the highs would come on for a few minutes and go off. They would come back on after being off a while. With this new switch they are not coming back on at all. They came on one time and after the usual time they turned off and never came back on.

There is a small box near the voltage regulator with I believe 3 wires going into it through a small plug. It is part of the lighting system no doubt but what is it? Is it the circuit breaker? The terminals are corroded and one broke loose from the unit so I know that, at least, is one problem. I broke that terminal last night but my headlights still burn on low so it seems what ever I broke was already out of commission.

Oh! I have a new dimmer switch as well..

Any thoughts?

 

Taking a guess you have a bad wire or fuseable link kinda thing happening. Sounds like something is loosing continuity when it gets hot, and then works when its cooled down again. The new switch may have gave it full juice and fried it completely. Just a possible scenario. I don't know what the box would be since I'm not familiar with all the new high tech stuff on the 1966 model. That corrodid connector might have been the problem though.

If that isn't it, I'd check the whole high beam system for a short, section by section. A short should be easier to find now that they don't come on at all.

 

Something else to check is your dimmer switch. When I moved from Texas to Nevada my dimmer switch went bad. The brights would work but the low beams would come on and off like it had a loose wire. I stopped someplace in Arizona and this old greybeard Harley rider had me check it and then put a temporary jump on it for me. When I replaced the switch later everything was fine.

 

The three prong box up by your regulator is your horn relay, so you can forget about that one. The switch that you replaced is the one on the floor, right?

The "dimmer" as you say in the dash, which you pull for the lights to go on, is actually the main switch. That era of engineering is a little dumb, as it runs all the current of the lights through the switch. That switch, the "dimmer" also has a thermal overload.

What was happening before is you were having a high current draw when you had the high beams on, which was throwing the breaker or thermal overload in the switch. Once it cooled back down, the lights would come back on. Since the low beams draw less current, they were not throwing the breaker. Or, possibly, there is a short JUST in the high beam side of the wiring.

You said that after you installed the new high/low switch the lights came on once, then went out and never came back on again. High and low BOTH gone now, or just the highs out? If just the highs are gone, then the problem is in the wiring from the high/low switch to the lights, and now it is completely fried off. If both are gone, then I suspect you finally fried your dash/dimmer switch completely (as in the thermal overload is no longer wakeing back up after it cools down).

BUT, don't just replace the switch on the dash, as I am afraid you have a short somewhere that was causeing all your trouble and may have fried the switch on the dash. Hate to repeat it with a new one. Of course, a wiring diagram is a swell idea. Have you got one? Get a tube of dielectric grease as well, and take apart the connectors on the firewall, clean em up and spareingly coat with diaelectric grease, then re-assemble.

If this all gets to frustrating you too much, there is a tech article here at FTE about how to re-wire your lights to use relays. This results in much less current through the switch and brighter ligts. But it clutters the engine bay some more with new wires and relays. Pends on your priorities.

Don't you love your old truck!!!!! You will feel a HUGE sense of accomplishment when you have all this stuff working. Its like bringing the dead back to life.

 

I don't remember refering to the dimmer as being in the dash but anyway I have replaced the headlight switch "main switch" and the dimmer in the floor. Thanks for the great info on some other things I didnt know like the horn relay. I assumed this may have been a circuit breaker because when I was working on the lights it seems like when I had the "horn relay" unplugged that the lights would not come on at all. My low beams work fine by the way. When I plugged the relay back in they came on/ or at least I thought thats what was happening. The horn relay theory is more logical than my possible mistake.

The thing you said about possibly burning out the new switch could be the whole thing in a nutshell. You see I found that several of the spade terminals inside the headlight switch plug were marginal connections at best. Some were loose enough that they would have fallen off if they werent held in by the plastic connector. In other words a bunch of high resistance connections. Bas news in any circuit. I'm thinking the new aftermarket junk parts thermal breaker just can't handle what the old one could and thus refuses to reset. If that were the case wouldnt I be missing both high and low? Or is there a seperate breaker for each?

 

Think of it this way when you pull the headlight switch on it energizes one of the three wires going to the dimmer switch, the dimmer switch then directs the current to either high or low beam based on which mode it is in. Bad plugs at the floor mounted switchescn cause problems. I suggest this pull the plug off the floor switch take a piece of wire or a cotter pin and jump across from the live terminal to the either of the others. one should light high beam and one low beam. You'll need a test light to see which is enrgized when you pull the main switch on. By the way the circuit breaker for
headlights on the old stuff was in the main switch.

 

OK, now I understand what you meant by dimmer switch. I think of dimmer switch as a rheostat, but never mind.

If you still have low beams, then your problem is down stream from the high/low switch on the floor. Take that thing out again and make sure the connections are ok.

Could it be that someone modified your wiring and the thing that I though was your horn relay is not original? Adding a relay to high beams is not a bad idea, as noted above. Maybe someone did it years ago and now its craping out?

 

[QUOTE=cdherman]
Could it be that someone modified your wiring and the thing that I though was your horn relay is not original?[/OTE]

No I was completely mistaken. A local "mechanic" came in my store and I mentioned it to him and he told me he had one on some old truck and would bring it to my store. He did. Nice guy but its hard to believe that there so many people out there running garages with little or no formal training. He mentioned to me that this horn relay controls several things including the regulator. He never mentioned the horn. Glad I'm not paying him by the hour to fix my horn. I probably have more training than half the "mechanics" in my area. I was a military mechanic and have been ASE certified in two fields. I ask some dumb questions because I am new to the old Ford trucks and with the great pool of knowledge here why not ask. I'm not proud!

As far as my wiring everything seems to be in wonderful original condition. No molestations thank god! No local mechanic work.

Anybody who owns an old Ford needs to individually take the spade connectors out of the headlight switch socket and give them a squeeze with a pair of pliars. Gives a nice snug low resistance connection.

Thanks again for the help!!