High Beams stick on.

Old Henry

Old Henry

Well-known member
My only nagging mechanical problem on my road trip a week ago was, after driving in the rain for a while at night, my high beam headlights stuck on such that, when I pushed the floor switch to change to low beam, the low beams came on but the high beams also stayed on. So, both were on. Pretty annoying.

I've had this problem sporadically for about a year when it's wet. I replaced the floor switch thinking the original that was still in there had gone bad but I got the same problem with the new one plus it was much stiffer to push so I put the old one back in. I checked the wiring coming off of the switch. The insulation was pretty bad on it so I wrapped all of the bare wire with tape back to good healthy insulation. Still had the problem last weekend.

My thought is, how to waterproof the switch and wires coming out of it and wonder if there is some kind of heat shrink wrap large enough to fit over the entire switch, terminals, and wire for a few inches that would shrink enough to tighten around all of it to water proof it. If anyone knows of any or has other ideas please let me know.
 
Hi Henry
I would consider replacing the harness.
I know you want it to remain as original as
possible, but if the insulation is bad in that
one area, it's probably bad in others as well.
 
There comes a time when wiring needs to be replaced. Sounds like the high beam wire is coming in contact with the low beam wire due to the bad insulation. Bad or old wiring can lead to a fire. That's something you do not want to have happen. As much as you drive your Ford you should invest in a new harness. Without a new harness you are going to start having other electrical issues. There comes a time when being "thrifty" could cost you a lot more than you anticipated.
 
Since it seems that it only happens when it's raining, it's would seem that the problem exists where some thing can get wet. I'm unfamiliar where the high beam switch is on a 47, but if it's not in a location that it can get wet it's probably the wiring some where outside. Check the wires at the headlights, perhaps the water is making a bridge between the high and low terminals or the wires at the headlight or headlights, or even on the inner fender panel..
 
Cloth wound wiring, the cloth is not repelling water and when wet shorting between high beam wire and low beam wire. When dry it goes back to providing enough insulating properly to work correctly.
 
I was working my trans fix and someone had changed the high low switch.
Two parts on the Bay, brings the switch inside and will end your problem.

271797207241
281993374311 epay
 
George/Maine said:
I was working my trans fix and someone had changed the high low switch.
Two parts on the Bay, brings the switch inside and will end your problem.

271797207241
281993374311 epay
Click to expand...

Not if it's a wiring problem, only if its a switch problem.
 
paul2748 said:
Since it seems that it only happens when it's raining, it's would seem that the problem exists where some thing can get wet. I'm unfamiliar where the high beam switch is on a 47, but if it's not in a location that it can get wet it's probably the wiring some where outside. Check the wires at the headlights, perhaps the water is making a bridge between the high and low terminals or the wires at the headlight or headlights, or even on the inner fender panel..
Click to expand...

JSeery said:
Cloth wound wiring, the cloth is not repelling water and when wet shorting between high beam wire and low beam wire. When dry it goes back to providing enough insulating properly to work correctly.
Click to expand...

The switch is under the floor right in the splash pattern from the front left tire so I gets plenty of water when the road is wet.

I had concluded some time ago the same thing as JSeery - that wet cloth insulation was letting current leak between the wires. That's why I asked how to waterproof the switch and wiring in that splash pattern. The only problem with the theory is, if that's what's happening, why don't both filaments stay on all the time instead of just the bright circuit? If the bright circuit is powered from a short to the dim circuit, the dim circuit should, likewise, be powered by the bright circuit. That's a mystery. That must mean that the bright circuit is actually shorting to some other source than the dim circuit. :cool: Maybe it's nothing to do with the switch or the wires in that area. Maybe it's somewhere else that's getting wet and shorting. I'm just not sure where that would be since that switch area is the only wet spot on that circuit. I'll have to keep pondering on that.
 
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Old Henry said:
The only problem with the theory is, if that's what's happening, why don't both filaments stay on all the time instead of just the bright circuit? If the bright circuit is powered from a short to the dim circuit, the dim circuit should, likewise, be powered by the bright circuit.
Click to expand...

That's a good point Henry.
 
How can you tell that both at energized at the same time? It seems that the bright side would overpower the dim.
 
40cpe said:
How can you tell that both at energized at the same time? It seems that the bright side would overpower the dim.
Click to expand...

Actually, my "dim" (low beam) lights seem brighter because they're shining on the road closer to the car. When I push the switch to change from high beam to low beam, the high beam indicator on the speedometer is still lit (although dimly), low beams are now shining low and close to the car plus the light further down the road from the high beams is still there and the oncoming cars are flashing their brights at me to get me to dim my lights.
 
From what you describe it seems that somewhere the water is making a connection between the high and low beam circuit. Could be at a wire or at the switch. I guess the only way to check is to wet down the circuit a little at a time to try to pin point the spot.

Since the switch itself has been changed with no difference, it isn't the switch per se.
 
paul2748 said:
From what you describe it seems that somewhere the water is making a connection between the high and low beam circuit. Could be at a wire or at the switch. I guess the only way to check is to wet down the circuit a little at a time to try to pin point the spot.

Since the switch itself has been changed with no difference, it isn't the switch per se.
Click to expand...

That sounds like a good idea to me. Might start at the front of the car and wet down the wires across the front. Then a foot of so at a time starting back toward the switch. See where the problem starts.
 
paul2748 said:
From what you describe it seems that somewhere the water is making a connection between the high and low beam circuit. Could be at a wire or at the switch. I guess the only way to check is to wet down the circuit a little at a time to try to pin point the spot.

Since the switch itself has been changed with no difference, it isn't the switch per se.
Click to expand...

JSeery said:
That sounds like a good idea to me. Might start at the front of the car and wet down the wires across the front. Then a foot of so at a time starting back toward the switch. See where the problem starts.
Click to expand...

Great idea. I may do just that.
 
Hi Old Henry,
I had a similar problem with trailer lights plug in my pickup. Was having problems isolating the problem like you are. I ended up putting silicone on the back of the female receptacle to waterproof this and that cured the problem with wet weather. Maybe you could do that on the back of the switch just help find where the problem actually is. The silicone can be cleaned off later for a permanent fix.
 
Sure sounds like a short between the high and low circuits, especially if your high beam indicator glows dimly and your circuit breaker is not cutting-out (contact to ground).

To waterproof wires and wire connections I use that "Liquid Wire Insulation" sold at Radio Shack as well as auto parts stores. The liquid is a rubbery black-colored acetone base brush-on. Apply at least 2 or 3 coats allowing each to dry before applying the next. Its very sticky and adheres well to anything. I used it on my back-up light switch and its wire terminals that are located at the base on the steering column, as well as general locations to prevent shorts. Good to protect wire where exposed to rubbing against metal i.e. horn wire at steering column base and routed thru frame openings.

If you want to better protect your foot switch from road-water, use the Liquid Insulation OR see if a plastic electrical box can be cut and trimmed to fit around the foot switch and its wiring, and caulk any openings and gaps to make it water tight. Although the latter is a non-ford/auto solution, the only person who will see is that guy you just ran-over.
 
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Drbrown has the right idea. You can also use some plastic dip coating for plier handles and it comes in different colors
 
Being that you mentioned the high beam indicator is glowing dimly would indicate a ground problem. Are both headlight bulbs on both high and low beam when the problem occurs? If not maybe a ground problem on one of the bulbs or sockets.
 
May be water getting in the light bucket. This should not cause a problem unless there are some issues. Have you tried installing new (or different at least) bulbs? It could be that simple. probably not, but, could be.
 
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