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Trunk light wiring
#1
I just installed the OEM trunk light, part number "D1ZB-13A756-BC "
its connected to the wiring harness over the rear driversside wheel well. (grn/yel).
the issue is that I always mesure 12v at the light fixture with the trunk lid open or closed, I checked the wiring diagrams for 1972 its section D59, it says Mercury switch, is the mercury switch built in to the fixture? do they go bad? could I have the wrong bulb in the fixture?

Thanks


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[Image: 2zem9nk.jpg]
Iyman
1972 Mustang convertible run_horse  
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#2
In my 1992 F-150 there is a switch built into the light socket. I think that is what they are refering to. The light on my pickup always has 12V all the time as well, but the switch in the socket is supposed to use gravity to recognize when the hood is open. It works fine but sometimes the light will flicker under the hood on rough roads.

run_horseI have always loved 1970 Mustangs, but how can a car I don't own trump the one I can drive? One in the hand...
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#3
The ball of mercury moves back and forth in the light socket/switch assembly, covering or uncovering the contact inside. The position and angle is critical, so the contact is uncoverd when the trunk is closed, and makes contact when open. You can easily find the correct angle with a volt/ohm meter.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#4
Yup, the mercury switch is in the bulb socket. To test it, disconnect the bulb socket assembly from the bracket, but keep the ground wire connected. If no ground wire, use a jumper cable to connect the bracket to the car's chassis. Now rotate the bulb around in various angles: ten to one you'll find the bulb will go on and off depending upon the angle of the dangle of the socket assembly.
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#5
I got it working, first I had the wrong bulb in the fixture the correct one is #631
second it was an angle thing, with the trunk fully closed its off.I took the back seat out to verify it.

Great, now I can see whats in the trunk at night Smile

[Image: 2zem9nk.jpg]
Iyman
1972 Mustang convertible run_horse  
Visit the Mustang Car Club of New England Facebook Page

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#6
imusa76;79434 Wrote:I got it working, first I had the wrong bulb in the fixture the correct one is #631
second it was an angle thing, with the trunk fully closed its off.I took the back seat out to verify it.

Great, now I can see whats in the trunk at night Smile

Mine you could see the ground...lol...really need to get that trunk pan installed...whistling
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