'41 ford trunk compartment light
- Thread starter fordor41
- Start date
adileo
Well-known member
Thanks JS. I was thinking if you remove the Mercury there would be a void that would need to be filled some how. I'll take mine apart and see what I can come up with. Will share if I get to work. Ideally I'd like to hook/connect to dome light
supereal
Well-known member
The switch is inside the socket, and is a mercury (liquid metal) type, not to be confused with the car brand. The accessory under hood light is the same type. In many cases, the switch part has failed long ago Most just connect in the license plate lamp lead inside the trunk lid. The idea was to come on when the trunk lid or hood was opened. This could lead to a "parasitic" draw if the light stayed on, and many were connected directly to the license light wire so it would come on only when the lights were used. This accessory was probably devised to allow the dealer to get a bit more money when the postwar cars came out.
JSeery
Member Emeritus
Need to replace some of the internal parts with a spring to connect between the rear where the wire comes in the the S shaped contact on the bulb end. You will also need to place a plastic sleeve around the outside of the spring so that it can't come into contact with the case. Let me know if you want me to draw you up a diagram.
Connecting to a different light source requires re-wiring. You have to run a wire from the one doing into the light switch/socket to the wanted power source.
Last edited:
Old Henry
Well-known member
Here the fixture is disassembled showing the mercury switch inside.
You can see that the mercury switch is like a glass fuse. Just wrap it in tin foil and reinstall and the circuit will be complete.
supereal
Well-known member
To use the original lamp sock, pry it open and replace the mercury switch (the little cylinder) with a spacer, or solder the wire directly to the socket. If you run the lamp using the license plate feed, you will eliminate the problem of forgetting it with an inline switch.
JSeery
Member Emeritus
What I intended to say is I would use the tail/plate wire with a separate switch to turn the trunk light on and off (when the tail lights were on). If I was doing it and wanted to keep the look of the original lamp socket, I would find a mercury type of switch and place it out of sight so that it turned on when you opened the lid. A lot of different ways to accomplish that as well.
adileo
Well-known member
I took the stock switch apart. Added in a metal spacer to fill the void of the mecury switch I removed. Tried it direct to battery it works.
While I like the dome light idea. I can't find a way to wire it in after the switch and to the trunk. My plan now is to run a new wire (unless someone has a better idea) from dash to trunk light with an inline switch under dash.
While I like the dome light idea. I can't find a way to wire it in after the switch and to the trunk. My plan now is to run a new wire (unless someone has a better idea) from dash to trunk light with an inline switch under dash.
JSeery
Member Emeritus
That'll work, an added feature, if you want to go to the trouble, would be to put an LED indicator light in with the switch so you know when it's on.
fordor41
Well-known member
Mine looks exactly like yours except instead of a mercury switch inside it has a fiber square with a contact/wire,a coil spring and another fiber square, 2 piece split block at the end that is held in place with the 3 bent tabs. Also no insulator and no square with the S shaped contact .This is the original trunk light fixture that was in my 47 until the mercury switch quit working. The mercury switch is in the light fixture. When I could not find one exactly like it I replaced it with the style Mac's sells that I referred to earlier.
Here it is disassembled showing the mercury switch inside.
adileo
Well-known member
I like that idea. I went online and all I could find was 12v Led. Do they sell 6 volt Led switches?
fordor41
Well-known member
Ok, figured it out. 20 yrs ago I disassembled the trunk light because it didn't operate. I "thought" the mercury switch was a fuse and was no good, as I checked it with a meter,so I reassembled the parts to make the bulb light. Dummy me I should have tipped it to operate the switch. I believe it's still in my garage somewhere and will try it again. Like the idea of powering with the interior lights. Thanks guys
Old Henry
Well-known member
Rather than trying to incorporate the LED light in the switch, the switch could be hidden under the dash and a separate small LED mounted under the dash to show.
This is my electric backup fuel pump switch on the left that lights the red LED and the fog light switch that lights the yellow LED.
From the driving position you don't see the switch, just the light. The green LED right of the steering column reminds me to turn off the kill switch relay when I turn the engine off.
LED is from Radio Shack. https://www.radioshack.com/products/green-led-with-holder-1?variant=5717557253 They're called 12 volt but work with 6 volts.
So is the switch. https://www.radioshack.com/products/spst-micromini-sw?variant=5717516293
The small LED lights can be stuck anywhere you want with this:
Don't laugh. It works. It is hardly visible and never comes loose nor falls down, unless you want to relocate it like I did the pump light from the second picture to the first one when I added the fog light LED. Then it's easily detached and moved.
Last edited:
Old Henry
Well-known member
You can easily resurrect the tilt switch by adding one of the many mini mercury tilt switches available. https://www.google.com/#q=mercury+switch They won't fit inside of the original fixture but could be attached to it with circuit going through it from the license plate light wire as original. Then, when you want the trunk light on, you just pull the headlight switch to either park or headlights and open the trunk. That's what I do and how it was designed to work. Way easier than running some separate power wire from the front of the car to the trunk light.
4dFord/SC
Well-known member
Replace the mercury switch with a short piece of copper wire or other conductor, like a small metal spring.
Bob-93021
Member
My trunk light in my 47 sedan was not working. From the wiring diagram I see that it gets it power from the tail lamp circuit. I found the Mercury switch was defective. I would like to rebuild the stock unit if possible. Later model Fords and GM used a similar Mercury switch. I have one from a 1997. It has a similar cylinder in it. I think that this could be re-used in our original bracket. Another project that is on my to do list. I have never posted pix here but will give it a try. (hope it works) - Bob
