63 Impala SS trunk lamp bulb

#1
I in the process of replacing the rear Body harness in the car. Using two harness from American Autowire.When I hooked the trunk lamp noticed it was continually on. I checked the assembly and service manual, both show a 20B lead. The connector in my harness is a 20 orange..Also has a plug in the harness in the trunk where the rear trunk harness plugs in. The other thing is none of the manuals show a replacement number for the trunk lamp. I did check that when the trunk is closed the light goes off. Is it a special lamp and does the SS for 63 use a different configuration? Anyone else run into this?
 

pvs409

Well Known Member
Supporting Member 8
#3
The trunk light on all 1961 to 1964's (all models) that came from the factory with trunk light, have a mercury switch inside the socket that shuts off the light when the trunk is lowered. Thats right Mercury inside the socket......
Only original or NOS GM trunk lights have the Mercury switch in the socket. Impalas typically got the factory trunk light.


The bulb is a # 93 (original number) that I have in my 62's -That bulb is listed on my 1962 shop manual as luggage lamp.

The original and American Autowire wire "for the trunk light" is a black wire from the trunk wiring harness (this harness has the 4 trunk taillights ) is black and plugs into the trunk harness with male and female plastic connectors.
Also the trunk light plug in has a metal clip to hold the clip "to hold the connection plug in" to the metal trunk wall at a access hole in the trunk.

The headlites or park lights must be turned on for the factory trunk light to work.

I am not sure the reproduction trunk lights have the Mercury shut off and turn on -I bet they do not have this feature...
The reproduction trunk lights do not have the two metal strips on the socket to to protect the light bulb from being hit

I can post pictures.

Paul
 
#4
Thanks for the info! I looked at the socket...It does not appear to be special,never figured it contains a mercury switch. I traced the orange feed 12volts constant, fed by the fuse that feeds the courtesy and dome lamps.it appears that this change was made so that the lamp will work without the tail lamps on. The lamp I have has the two bars to protect the bulb. Thanks again John
 

Carl 1962

Well Known Member
#5
I think it's the same mercury switch bulb socket as in the optional engine bay light attached to underside of hood and also only activated when hood is up and park/headlights on. Paul confirm?
 

pvs409

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Supporting Member 8
#6
I think you are right Carl. I have a underhood light, never installed it, so I am not certain if its controlled by mercury.
I will compare both to see if the sockets look similar.
Paul
 

64ss409

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Supporting Member 9
#7
I just checked my 64. I don't think I have had the truck open for maybe 5 or 6 years. Anyway I hooked up the battery cable and opened the trunk. Nothing came on, in fact there was no light attached. Evidently it did not get replaced after the paint job. So I checked the orange/black wire coming into the truck lid. It is hot with the ignition and light switch off.
 

Carl 1962

Well Known Member
#8
Apparently some time during the 1963 model year, the trunk light went from being activated by the park/headlight circuit, to being live all the time, so when you open the trunk the light comes on when the mercury switch in the bulb housing activates the bulb.
 
#9
My assembly manual must be a early edition because it is not updated to reflect the orange lead for the trunk lamp always having power..I also started the clean up wiring under the dash. I have the orange and white lamp sockets under the dash that are for the courtesy lamps. I have the American Autowire courtesy lamp holders, but am not sure how to mount them. Again nothing in the assembly manual. If anyone has a 63 SS and could post pictures it would be a big help. One of the few bright spots of the lockdown is a lot of car hobby time.
 

pvs409

Well Known Member
Supporting Member 8
#10
There are predrilled factory holes in the bottom corners of the dash for the underdash lights. I assume you have the metal 3 sided socket holders for the lights - these factory mounts are zinc plated with philips mounting screws with fixed washers.
The socket holder brackets are screwed through the holes in the dash( you do not drill the bottom of the dash).
the wiring harness for the coutesy lights is part of the rear light harness - one long wire across under the dash for the passenger switch for the door jamb and short wire to drivers side.
 

Junky

Well Known Member
#11
In both the trunk and hood lamps there is a tiny vile of mercury under the bulb contact that when tipped completes the circuit. It is just like the mercury contact that used to be used in your wall mounted thermostat. I have no idea how the reproduction lights work, however, unless they have found a replacement liquid for mercury, I can't see how else they could function.
The interesting thing is that when we were kids, we played with mercury, and made copper pennies look like dimes by soaking the penny in the mercury. Back then, if you spilled some mercury, you just swept it up with a broom and a dust pan. Today, if you spill a drop of mercury in a school, they evacuate the building and call in a hazmat company to do the clean up for an outrageous amount of money. A few weeks ago, a friend asked me if I knew how to dispose of 20 +- pounds of mercury. I did a quick google search to see where he could sell it, and it appears that it is no longer purchased by the scrap metal dealers. 50 years ago, mercury was kept in steel bottles (flask) with a threaded cap, and when full, they weighed about 80 pound plus the flask. My dad was in the scrap metal business, and I routinely would pick up or drop off flasks of mercury at other dealers that were in the trade. In the 1960's I think it was worth about $190 for a flask. In 2016 it was over $4000 a flask.
 
#12
My assembly manual must be a early edition because it is not updated to reflect the orange lead for the trunk lamp always having power..I also started the clean up wiring under the dash. I have the orange and white lamp sockets under the dash that are for the courtesy lamps. I have the American Autowire courtesy lamp holders, but am not sure how to mount them. Again nothing in the assembly manual. If anyone has a 63 SS and could post pictures it would be a big help. One of the few bright spots of the lockdown is a lot of car hobby time.
 
#13
I am still trying to figure how to position the courtesy lamp bracket on the drivers side. I have two holes under the dash along with the opening. I am assuming the light points toward the front of the car. Which hole is the correct one to use. Also I assume the bracket goes on the inside of the dash. No problem on the passenger side.
 

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Jim Sullivan

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Supporting Member 8
#16
I am still trying to figure how to position the courtesy lamp bracket on the drivers side. I have two holes under the dash along with the opening. I am assuming the light points toward the front of the car. Which hole is the correct one to use. Also I assume the bracket goes on the inside of the dash. No problem on the passenger side.
That rectangular hole looks like a convertible top switch mounting hole. :dunno2
 

Junky

Well Known Member
#17
Here is the breakdown of a mercury switch light in what I believe is a trunk application. This light had the wire pulled out of it, so I decided to dissect it for the photo. If you recognize the application of this light, please let me know.. thanks Junky MVC-010L.JPG
 

pvs409

Well Known Member
Supporting Member 8
#18
That is a factory trunk light for 1961 to 64's to my knowledge.
All my cars have them, plus I have 2 to more of them -the wires like to pull out of them.
Paul
 

Junky

Well Known Member
#19
Might you be able to ID this one? It was in a box marked 1962, however, I know that the 1962 uses only one screw hole, not 2. I just repaired both of these with new pigtail wires. The biggest pain is to remember exactly how they go together. I had to take another one out of the box to figure it out.
Many years ago, I bought a box of replacement wires that go inside of the sockets, at a swap meet. They work perfectly in these lights, once you take them apart. Wish that I could find more of them.





MVC-001L.JPG MVC-002L.JPG
 
#20
The first lamp (one mounting hole) appears to be the same as in my 63 EXCEPT for the hopes going in different directions. The lamp in my trunk both hoopes both go in the same direction. When mounted they protect the lamp.
 
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