Headlight Switch

[Richard Cope]

Hi,

 

Want to replace the headlight switch on my 39 Ply.  I have an NOS one, can't locate a part # however  believe it is from a later year as it does not have a built in fuse ( will add a separate one) Other than the fuse, it appears very similar to the original, shaft appears to be the same.  Attached is a photo of the switch, does anyone  know the wiring layout for this switch?   Any ideas what the circular hole in the back of the switch is for? 

Thank you in advance for your help

 

Regards,

Richard

[Jerry Roberts]

The circular hole is for a light bulb . Are there any letters stamped by the terminals ?

[Richard Cope]

The front  terminals that have a brass strip connecting it to a back terminal seems to have an "R", which may represent low beam.  Red wires are for low beam and black for high beam.

[Sniper]

headlight switches should never use a fuse, go with a self resetting circuit breaker.

[Sam Buchanan]

2 hours ago, Sniper said:

headlight switches should never use a fuse, go with a self resetting circuit breaker.

 

Ok....for those of us that have a headlight switch with a built-in fuse, what are our options? What kind of breaker (part number, application,  current rating, etc) and where do we put it? In the lead between the ammeter and headlight switch? Then we put a slug or something in the switch fuse holder?

 

Or maybe a box of slow-blow fuses in the glove compartment........what size fuses are used in the switch?

Edited June 27, 2020 by Sam Buchanan

[Sniper]

They make breakers that fit into the fuse holder.  Use the same rating as the fuse.

 

https://tinyurl.com/y887d9sn

 

 

 

[Sam Buchanan]

Hmmm, gonna have to take a another look. Last time I looked it appeared the fuse was the same shape and size as a regular glass fuse, don't see how that rectangular fuse would fit the switch.

Edited June 27, 2020 by Sam Buchanan

[Sniper]

that rectangle isn't a fuse.  It's the breaker.  The copper loops you see goes where the glass fuse was.

 

Another style that also works https://www.carid.com/dorman/40a-circuit-breaker-fuse-clip-glass-mpn-85618.html

 

Pic installed

 

[Sam Buchanan]

Nope, won't work. Here is the fuse in the P15 headlight switch. There is a glass fuse in the cylindrical holder.

 

Edited June 27, 2020 by Sam Buchanan

[Richard Cope]

I agree,  this is my project.  Converting the car to 12 volt, neg ground, will be using a 12 volt generator / voltage regulator from a 50s Ply.  Rhode Island wiring gave me the colors and wire gauge used on the 39 Ply.  &  from that purchased enough wire to do the car.  Didn't purchase a stock harness as want to add a panel box. .  Currently the car has two stock fuses, one at the light switch & another at the horn.  I have added fuses to the radio and heater fan, if one doesn't know where they are at would take some time.   Currently using a 12 v Opinum  battery in back i to power radiator pusher fan, radio,  heater fan and gas gauge which have been converted to 12 v.   Ordered  Ron Francis Express panel box for it is front load and can use the  reproduction wires also ordered the drop down kit.  There isn't much space on the kick panel & the drop down kit will help to get to.  Also going to be adding the crash shut off for the electric fuel pump.  Also sells a heat shrink wire bradding that looks & feels to the cloth bradding, attaching a photo of. Want to use my stock headlight knob.  Since the current one has a fuse, purchased the one in the photo for my stock knob will still work.  Perhaps the other option will be to eliminate the fuse in the stock switch.  My goal to keep the stock appearance but improve the safety and reliability.  Currently using 6 volt headlight relays, work great but finding not too dependable.  The fuel  gauge is a one wire Ford gauge with my face plate attached, much easier to work with that the two wire used in the original.    Had the original radio rebuilt twice and the third time, tubes were removed and replaced with a circuit board, works better and less electrical draw.  

[Sniper]

22 minutes ago, Sam Buchanan said:

Nope, won't work. Here is the fuse in the P15 headlight switch. There is a glass fuse in the cylindrical holder.

 

 

Guess what happens when that fuse blows?

 

You walk.

[Sam Buchanan]

12 minutes ago, Sniper said:

 

Guess what happens when that fuse blows?

 

You walk.

 

No, just the lights go out. The ignition is wired hot with no fuse.....you can still hold a good flashlight out the window.......or get another motorist to fly formation with you.......   ?

 

I agree that having all lights on one fuse isn't the best arrangement, that is why I mentioned replacing it with a breaker. But a breaker will have to be mounted somewhere other than the switch and I assume in the line between the ammeter and switch. The other option is the addition of a fuse panel that breaks out individual lighting circuits through separate fuses. That involves major changes to the wiring architecture.

 

But....if a breaker trips there is a problem that is best addressed with the AAA card......    ?

Edited June 27, 2020 by Sam Buchanan

[Richard Cope]

Since the 39 only has one fuse if it goes out you are not only in the dark, but have to determine what caused it to blow which could be anywhere on the car.  I also like the idea of an electrical shut off incase of an accident, uses the Ford design.  For those rewiring their car may also want to look at RF's "grey matter" a plastic channel that glues to the floor to run wires through, is about the thickness of insulation.  The stock harness went behind the headliner,  on the floor will give shorter runs.  Does anyone know the year that the light switch pictured was used in, perhaps , I could get a wiring diagram for that year to see where the connections go to.  I will only be using for the headlights

 

Thanks Rich

[greg g]

The fuse is a 30 amp but it is not a SFE.  I believe they are AGC.  They are slightly longer and thinner than the SAE type.  Used to get them from radio shack but they are out of business. 

[Plymouthy Adams]

10 hours ago, Richard Cope said:

The front  terminals that have a brass strip connecting it to a back terminal seems to have an "R", which may represent low beam.  Red wires are for low beam and black for high beam.

 

First....it is confusing how you state the colors for low beam and high beam on the H/L switch when the selection of beams is a function of the dimmer switch fed by a single wire off the H/L switch.  I am thinking you are confusing park lights circuit for what you calling low beams.  You also mention using H/L relays...as in more than one...you do not need but a single relay and you have two manner in which you can control that current, supply to dimmer....or dimmer to relay and utilize the NO and NC contacts as they were designed to function.  

 

you should have main feed B+ coming in and note that the H/L switch function as a buss bar and the fuse or breaker as equipped interrupts this buss. this buss will feed to courtesy lights if equipped and also to the brake lights,  could be other constant power circuits picking up power you will have wires feeding dash lights at first step of the switch and on to parking lights, then you will have the main heavy wire out for headlight that feeds the dimmer.

 

as for the concern of fuse or breaker...you can easily put an inline breaker to the main input  and the RV stores in your area have these if you big box does not...

Edited June 27, 2020 by Plymouthy Adams

[Sam Buchanan]

6 minutes ago, greg g said:

The fuse is a 30 amp but it is not a SFE.  I believe they are AGC.  They are slightly longer and thinner than the SAE type.  Used to get them from radio shack but they are out of business. 

 

Thanks, Greg, I'll pull mine to check it and put a couple of spares in the glove box. But if the fuse blows, the replacement almost certainly will, too.....

Edited June 27, 2020 by Sam Buchanan

[Plymouthy Adams]

1 minute ago, Sam Buchanan said:

 

Thanks, Greg, I'll pull mine and put a couple of spares in the glove box. But if the fuse blows, the replacement almost certainly will, too.....

there in lies the very success also of cleaning your wiring contacts...it is often loose or high resistance dirty connection that pull excess current...also the contact within an older switch with these contacts worn and tension comprised along with dirt/corrosion over the years adds resistance and in turn, added current.  This is the single most argument for switching the headlights themselves as the highest current consuming items to be fed from the relay  and allow the switch ONLY TO CONTOL coil circuit pf the relay.  

[Sam Buchanan]

On a related note. Is there a "modern" replacement headlight switch that can be adapted to our original knob? The parking light step in my switch doesn't work and it may just be a matter of time before the headlight position gets flaky.

[Plymouthy Adams]

yes...not the modern rotary we have on so many but through the 80's for most part still  had the pull knob....this knob is released from the switch by a spring loaded button...one you release this you can eliminate the knob from the shaft and position you exiting knob in place once the length is determined correct....you may however find that the retainer is often female on the later switch and not male like the older...this may not set with you cosmetically....often there is a trade of.  Personally I feel these older switch are still good components when you remove the high current and allow the switch to control the relay coil and the relay do its job of controlling the high current.  The subtle wiring change is never noticed by anyone unless they look under you dash..then a quick karate chop is smoothly executed by yourself...all problems solved.

Edited June 27, 2020 by Plymouthy Adams

[Richard Cope]

I was trying to compare the light switch to the stock 39 switch.  For the 39 red wire are  used for the low beams and black wire for the high beam throughout , the stock switch only has four post, one marked R and another marked B for these wires, whereas the new switch has 5 unmarked terminals.   The headlight relays (a separate box) worked great gave brighter headlight,  however last summer low beams on one relay quit working  replaced and a month later high beam went out on another even though they were new had been sitting round for may years.  Not difficult to replace, but as expected stopped working at inconvenient times.  With a panel box will be able to use a modern cube that can be replaced in minutes. 

[greg g]

I have repowered my brake light switch directly from the battery side solenoid terminal.  I have 35 watts halogen running lights and 50 watt halogen buls in all three rear lamps.  This load when added to headlamps would many times blow the switch fuse.  The wire from power to the brake switch hasa 25 amp inline blade fuse. Haven't blown either fuse since this mod was done.  Also cleaned all the connections in the headlight terminal block and relocated the head lamp grounds to new clean metal.  And finally found an NOS dimmer switch that was wrapped in a treated paper envelope.  This got rid of a lot of resistance and since watts is watts, my 6v headlights are as bright as the 12v sealed beams in the heater.

Edited June 27, 2020 by greg g

[Plymouthy Adams]

not to add any more confusion but the build I am currently deep into will not allow the use of the stock dimmer switch....the work around is done by suing a relay where NC and NO contact do the high current deed but in addition the dimmer switch is the main change.  It is now a small momentary switch built into the shifter knob and triggers a bi-stable relay.  Smooth easy fix, the head light will always default to low beams when head lights turn on...these are also feed by a 8 circuit fuse box to upgrade a car that factory had but three fuses and one of which is an inline.

[Los_Control]

Stupid idea here ... would it be feasible to replace the light switch fuse with a slug, then just add a breaker inline going to the switch?

Maybe I am missing something. here and not understanding the subject.

[Sam Buchanan]

Just now, Los_Control said:

Stupid idea here ... would it be feasible to replace the light switch fuse with a slug, then just add a breaker inline going to the switch?

Maybe I am missing something. here and not understanding the subject.

 

That is the exactly the stupid idea I have been considering.....and suggested in post #5.   ?

[greg g]

Yes wrap the old fuse with an aluminum foil gum wrapper and fuget aboudit.  As long as the circuit or the power to the loads are protected, it doesn't seem the where would be an issue.  So relays or in line would do the trick.

Edited June 27, 2020 by greg g