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Headlight Switch


Richard Cope

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23 minutes ago, Richard Cope said:

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. 

 

 

Per my 39 schematics...yellow wire is out from the light switch to the dimmer as the single feed for the selection of high/low beams and attaches to H terminal of the switch  post B input is brown wire...A and R feeds the parking lights A to front terminal strip and R to the rear lights....and not sure but are not these front parking lights part of the h/l assembly for 39 and while not low beam but JUST park light instead.   D will feed the switch for the instrument lights.  

 

amended

Edited by Plymouthy Adams
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14 minutes ago, greg g said:

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.

 

this is what you use your left over brake lines for....small fuse sized cut lengths.....it amazes me yet I still find this done in some of the older cars at the junk yard...they are easiest found as most look like a hunk of charcoal. 

Edited by Plymouthy Adams
  • Haha 2
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Thanks for all of your feedback, will go under the dash later today to see just how the current switch is wired.  Also have an NOS stock switch, like the idea of using it and block off the fuse.  Would only be used for the headlights and circuit will be fused at panel box.  Original know would work.

 

Thanks,

 

Rich

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"R" is for "Rear".  Here's a photo of my 47 DeSoto headlight switch.  I checked my wiring diagram.

 

"H" - Headlights, to dimmer switch    "A"  Front Parking Lights

"R" - Rear Running Lights                    "D"  Dashboard Lights, to the dashboard on-off switch.  


The bar to the right is the power supply, through a circuit breaker.  Power goes to the post on the right of the circuit breaker.  Dome lights and stop lights are wired to the left post, and are protected by the same circuit breaker as the headlights.

 

(At one time I bought and installed a vintage headlight relay, which has separate contacts for the low and high beams.   So the switch does not carry the amperage of the headlights.) 

 

254551101_headlightswitch(3).JPG.201f5ff59f8cb5dba0846114ba22d7d8.JPG

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13 hours ago, Richard Cope said:

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

Light Switch 1.png

 

The hole is for a bulb which when the car is using high beam will come on and send light down the shaft of the switch to the knob. There should be a small glass circle in the middle of the knob and this will show the light and that high beams are on.

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On 6/27/2020 at 9:03 AM, 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. 

 

The fuse in my headlight switch appears to be a SFE 30a (1/4" x 1 7/16"). The 30a AGC is shorter. My local NAPA store has them in stock.

Edited by Sam Buchanan
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Don. Thanks for the info.

 

The lettering on my switch in the photo is verily  readable, able to read the R & A, however the layout  is close enough to your switch that can determine the other terminals.   Haven't decided yet if going to use the NOS 39 Ply switch and block out the fuse or use the newer switch similar to yours without a switch. 

 

Regards,

 

Rich

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If the electrical setup in the attached photo looks familiar to anyone, appreciate letting me know.  Based on yesterday's discussion, I labeled the contact post of the switch that I am interested in, see attached.   Don't have a part number & can only read "R"  for one of the terminals which labeled as rear running light.  Did a bench test and everything works correctly with this pattern.  The switch is a Mopar used in the late 40s.  Does anyone recognize it and can verify the electrical connections or give the year and model of the car used in.  My goal is to replace the headlight switch in my 39 Ply. which contains one of only two fuse in the whole car and will add a panel box with fuses.

Regards,

 

RC 

Headlight Switch Post ID.png

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Rich:  This switch is for around 1937/38 and not the 40s.  The 37/ desoto had a drawer pull type button so when the light was pulled on these was a whole in the drawer pull that told the driver the light where on.  In the panel light the same affect.  In 39 They changed the switch to be the clip on knob style just like on my 39 Desoto.

 

rich hartung

desoto1939@aol.com

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  • 2 years later...

Fuses fatigue over time, especially if they are carrying near their current limit.  Did you upgrade the headlight bulbs? Have tail light brake lights been added to the circuit?  (cars in the forties only had the trunk mounted lighr for brakes. Many people later added dual contact sockets in the tail lights to add brake lights.)  .... Just a couple of things to check.

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