I have posted on this before but heres the update. I have no high beams at all. With the old headlight switch I used to get highs for a few minutes. With a new switch I got the same effect a couple of times and then they went out for good. Since installing the new swich I discovered that most of the spade terminals in the switch socket were loose and I tightened them up. Realizing what a poor connection I had I thought maybe I fried the internal breaker in both switches so I got another. Same thing. Its NOT in the switch. We know that for sure. Earlier I had replaced the dimmer switch as well. That should not be the problem although as a parts man I know they can come out of the box bad. It was a Wells part. Not too bad. I guess maybe I can swap the old one back in if I still have it and see what happens. Knowing that both lights WILL burn I dont feel like the problem is outside the cab.

Any suggestions??

 

If its not either switch then you have a bad wire somewhere. Either that or a bad ground. Check the dimmer switch ground first. I had to plug the old holes and drill new ones when I changed my switch out.

 

There must be a broken wire or melted wire somewhere in the front harness. I'd trace it out to see . Usually if you had a bad ground, none of the headlamps would work. I'd check the grounds anyway, just to make sure they're clean. Have you jumped power to it at the dimmer switch? If you have and still no good, then it's most likely a bad wire.

Barry

 

Are you using a seal beam headlight or a newer halegen light? Or have you changed out the headlights?

 

If you have a poor ground at the headlights themselves it could cause the circuit to fail when power is applied, it can't pass enough current to power the lights. Check grounds first then trace the light harness and look for any dicolorization, chafing, or bad connectors.

 

I think I have two sealed beam halogens. Many folks get the halogen thing confused. Any new sealed beam you buy in a parts store is halogen. Except I think the 6 volt lamps that still are sold. They are what all sealed beams used to be. Incandescent. Basically the same thing as a bulb you screw in a lamp. A filament or two in a vacuum. As much of an improvement as halogen bulbs were over incandescent I am always amazed at the folks that come in my store wanting these blindingly bright lights marketed today for the "its all about me" crowd of modern America. Sure its good to be able to see clearly but enough is enough. I am 35 and many times have been flash blinded at night passing some SUV or whatnot and I think what about all the 70 year old folks out there. At 35 I am having to guess where I am at in the road for 10 seconds when passing bling-bling. And I dont wear glasses.

Sorry! I vented. Anyhow as far as my truck I know the bulbs will burn because I have seen them burn. After replacing all the components anyone would through logical troubleshooting the problem is actually worse. Like I said before the highs originally would come on for a few minutes and go out. Now there are no highs at all...

 

Not to beat a dead horse.... but if the ground was bad at the headlamp, you'd not have any lights at all, high or low.They share the same ground. He states he has no high beam now. So, that means it has to be in the high beam part of the circuit. I would turn the headlamps on, Find which wire feeds the dimmer and take a jumper wire and touch it to one of the other 2 terminals on the plug. Something in the circuit should light up. Have someone stand in front and watch. Then touch the jumper to the other terminal. If it doesn't change in intensity, I'd say you have a break somewhere or a bad plug out in the harness. Get a meter and trace the wiring to see. I know it's a pain, but you don't want to keep throwing parts at it, hoping to fix it.

Barry

 

As I understand this saga, you originally had low beams and high beams, but the highs would only stay on for a few minutes and then go out. And then come back on after a while. So you replaced the dimmer switch, the one on the floor. And then your low beams still worked (and continue to do so?), but you switched on the high beams and after a few minutes they went out, one final last time.

Assuming that your lows still work, then the problem must be in the harness. It is not at the lights, as it would be quite unlikely for both lights to loose their gound at the same time, and besides, the low and high use the same gound. The short must have decided to fry itself off and now the wire to the high beam side is off. The break must be somewhere upstream of where the harness "forks" to the two lights as well.

 

Guys, Shouldn't you be able to place the third prong of the light on the neg post on the battery and run a small jumper over and test both high & low to see if the bulb is good?

John

 

That's what I've been saying right along...................

Barry

 

I figured it out. Some idiot cut into one of the wires going into the three prong plug at the dimmer switch. Reason? That is where he decided to tap into a power source for the FM converter. Why go under the floormat and cut into the headlight harness for a power source? What an idiot! Anyhow a little solder and high beams work fine. I need to use another source for power to the converter as I fear the extra load will throw the breaker. I'll find out when my original radio comes in the mail and I get everything hooked up. Thanks for all the info and advice. You know nearly every problem I have had with this truck was the result of botched repairs and upgrades. Sometimes when a vehicle is giving you trouble it all gets blamed on the vehicle when most of the time it all caused by the P.O.'s.

 

EVERY problem I've come across with my 65 is due to the previous owners stupidity. I've been working on this electrical nightmare for 11 months now. I'm just going to get a new harness as soon as I can afford it. Tired of chasing wires to find out that they have been spliced and then rerouted while the other half of the original wire went were it was supposed to

 

Gee, the wiring harness in my original 65 HAS a spare bullet connector that went to the radio stock. Like, why don't some people think to use the obvious source for the power!!!

Glad you got the lights working.

 

cd,
Definately NOT defending the tap into the light harness but the factory radio tap is only in the acc or on position. The PO must have been looking for a source of batt power to keep clock and preset functions stored.

 

I made a mistake. Upon further inspection I realized that the tapped wire ran to a toggle mounted where the hazzard light switch would be had my truck came with them. Anyhow the switch seems to be for fog lights. At least now I know this person had some measureable amount of sense. Enough to rig the fog lights up to work with the dimmer switch. This may make me sound stupid but I'm not proud. Wouldnt you want fog lamps to work with low beam lights. I mean you use low beams in heavy fog. If you wire them into the high beam circuit you would be defeating the purpose of a fog lamp. Unless all you want is max brightness when using highs.

That rubber 3 prong connector is a problem area in the notoriously troubled system. I have read a lot of stories of all the reasons why the truck headlight system has been known to be troublesome. Many theories out there, but really the system is no different than most any other automobile in the mid 20th century. I mean I rule out design flaw as the reason for Ford truck lights going out. If your truck is throwing the breaker or doing anything else bad pull the connector off of the headlight switch and individually pull each wire from the socket and give them a squeeze with a pair of pliars. Use a male spade terminal connector as a gauge. You will be surprised at how loose these connections are. The dimmer connector mentioned earlier has the flaw of only making contact on one side as opposed to male/female metal to metal. The 40 year old rubber is the only thing bearing pressure on these connections. I manipulated the male terminals on the switch a bit to add pressure. Ford used a three prong switch for years. New sockets should not be hard to find.

Greg