High Beams stick on.

I'm going to try to duplicate the conditions I have experienced out on the road here at home by wetting down sections of the headlight wiring starting from the bulbs to the switch to try to cause the problem so that I can pinpoint the location of it. Once I've created the short I will first turn the headlight switch off (I never tried that while driving with the problem). If that shuts off both beams I'll know the short is between the circuits. I may also disconnect the dim circuit from the switch and see if the bright circuit is still energized. That will tell me whether the bright circuit is shorting to the dim one or to something else.

I agree that the dimness of the bright circuit when I switch to the dim circuit looks like a ground problem so I'll be checking for that too.

I sure appreciate everyone's willingness to share every idea to help me solve this problem. What a great resource to have so many knowledgeable people available willing to help.
 
Things seem to point to wires rather than switch, but for whatever it's worth switches can oft be "rebuilt." Old Ford switches (of all sorts) in my experience are rarely worn out, but are rendered inop or unreliable by dirt and ancient lubes. They are worth rebuilding because they are generally of better quality than repros, some of which are 12 V and lack amperage capacity.
On the hi-lo switch most are die cast with a plastic terminal/contact plate. Careful massaging will bend the die cast crimps out of the way and allow innards to be examined, cleaned, and greased. Extra grease or Permatex where plastic meets metal should greatly enhance water resistance.
 
I'm making progress.

I put a hose sprinkler under the dimmer switch and let it run for 15 minutes - no fail, so, it's not the switch nor wiring in that area as I have always thought. I then put the sprinkler in front of the left wheel to water the light buckets in that fender area. Again, no fail. I then put the sprinkler in front of the right wheel. After just a few minutes BINGO! The problem came.

Now that I have the failure to examine more closely here's what I see. When the dimmer switch is on high beam, the right bulb is on bright high beam only but the left bulb is dim. When I switch to low beam both bulbs dim and appear to add the low beam filament to the high beam and the dash bright indicator light is on dim.

So, what do you think? I'm certainly going to check the grounds of both bulb fixtures and all wiring starting with the right bulb. Hopefully will find a obvious problem to fix.

Thanks to paul2738 and JSeery for the idea to wet down sections to re-create the problem to locate.
 
It was Paul's idea, I just agreed with him! Great example of the scientific method in action!! You know, it could be something like a ground problem of some type as well. Might check the ground on that headlight assembly over and the wiring in that area as well. Another thought is some type of corrosion in the lamp socket area that is acting up when damp.
 
Glad you found where the problem lies.. Add a temporary ground to the bucket and see how it works out. You might want to pull the bucket and examine all the wires and connections.
 
I think I got it fixed.

I removed both headlight bulbs to check the wiring inside of the bucket. The right light had a very old secondary ground wire from the light socket to the body. I replaced that with a new one. The left light had no secondary ground so I installed one. I watered it all up good again today and no problemos!

Don't know what the water had to do with anything but it's no longer causing a problem.

Thanks again to everyone for your help. I was headed totally the wrong direction with this until you came along.
 
Seems odd that it would be a ground wire. I could see a faulty ground wire leading to the lights not coming on, but making the high and low beams come on at the same time is a little different result.

If the switch is working like you said then no power (-) would be getting to one or the other circuit (high/low beam bulbs). Now if wires maybe lightly insulated or worn the power would jump to a near wire in the same condition, especially when wet.

But stranger things have and do happen. Glad you figured it out. Happy motoring.
 
Adding a theory :): I could see, if the insulation on one wire was badly exposed and the other only slightly, when the circuit with the badly insulated wire was turned on it would transfer more energy to complete a circuit with the wire that is only slightly worn. The slight worn wire wouldn't transfer as much energy resulting in a non-connection. Maybe explaining the reason it only happens when the low beams come on. Or maybe not...

Would like to know why or how a ground would do this. Just for curiosity sake.
 
When the ground is weak, the current seeks any path to ground, even through other circuits. I've struggled with that before. I hope that was the problem and that I fixed it for good. The next nighttime drive in the rain will tell the tale. The drive to Alaska may be the ultimate test.
 
I guess if those other circuits are not isolated well within a system. So then it was grounding out through the high beam jewel?
 
Tinker said:
Adding a theory :): I could see, if the insulation on one wire was badly exposed and the other only slightly, when the circuit with the badly insulated wire was turned on it would transfer more energy to complete a circuit with the wire that is only slightly worn. The slight worn wire wouldn't transfer as much energy resulting in a non-connection. Maybe explaining the reason it only happens when the low beams come on. Or maybe not...

Would like to know why or how a ground would do this. Just for curiosity sake.
Click to expand...

My perception while driving the car in the rain at night that the high beams worked fine by themselves but stayed on when I switched to low beam was inaccurate. It seemed that way while driving in the rain. But, when I watered everything down at home yesterday and caused the fail, it was obvious watching the headlights while my wife pushed the dimmer switch that it was very different from that. The left bulb, that lacked the secondary ground, was dim no matter what, indicating the poor ground (somehow triggered by water under the right fender???) The right bulb was only bright for high beam but dim for low that combined with high, another indicator of poor ground. Adding secondary ground wires fixed the problem although it doesn't really explain what the water had to do with anything.
 
Well anyway, glad you got it worked out OH.

Looking forward to seeing your Alaskan ford adventure.
 
Henry,

if possible why not try shrink wrap tubing, heat with a hair dryer, can't remember if those are bullet type connectors or male spades, if male spades not sure if you want to cut em off and put on shrink wrap the put new ones on? that's your call.
 
The fact that the right bucket had a secondary ground means that some one had a problem and added the ground. I guess that the additional ground over the years went bad, hence your trouble.
 
Shucky darn. It wasn't the grounds. It isn't fixed.

Did a little 373 mile overnighter with AnnaRae last night. Coming home today it rained most of the way. When we were about 30 miles from home I remarked to AnnaRae, "Nice we didn't have any mechanical problems." Almost immediately, I noticed my bright indicator on (I had the headlights on for visibility in the rain). I didn't need than so hit the dimmer switch, same old thing. The high bean indicator stayed on but dimmed. When I got home, had AnnaRae hit the dimmer while I watched. The brights were both working great but when she hit the switch to dim them they stayed on, slightly dimmed, and it looked like the low beams were trying to come on with them.

Shoot. Looks like it's back to the drawing board trying to figure this thing out.
 
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