1939 Cadillac dome light power

[funnytain]

I just joined the CLC group but don't have a membership number yet. My question is, my dome light in my 1939 60 special does not turn on when I want, it does when it wants. What I mean is if I flip the switch it does not come on, the other day I went out to the car and the battery was dead. It turns out the light came on and wore the battery down. I checked the switch and it is fine and there was power there. The next day I tried it and no power. I took it apart and no power on the wires and checked the switch which was good. Does anybody know where the feed comes from and the exact route to the door post where the switch is? I looked at the wiring diagram and it does not show the dome light circuit so is there an interlock or requirment to turn on the light?

Thanks!
Rick Fontaine
1939 Blue Cadillac 60 special

[Martin Michaels]

Rick, I am not sure about the 39's seeing they had a positive ground,on my '47 with negitive ground there is no power at the switch as they switched the grounds.(opened and closed the grounds) Not sure if this helps but it might be a place to start. Marty

[Brad Ipsen CLC #737]

40 and before had hot switches and starting in 41 and up the switches were for ground.  I think the hot feed for this comes from the body harness going up the right side A pillar from the dash area.  If this is old wiring it could be a frayed hot wire grounding out.

[C.R. Patton II]

Hello Rick

Welcome to the Cadillac & LaSalle Club!

Keep in my mind that we exist to assist you with answers, opinions, and history. Find a region or affiliate near your residence to experience the camaraderie and pageantry of membership. Please post pictures of your car.

I concur with the diagnosis by Brad.

[funnytain]

Thanks for the responses! I am not sure where the wire routing is so I can check the wire condition. Sounds like it is in the left side kick panel area. I am aware of the positive ground and when there was power it showed on the meter. I am trying to find the routing so I can check the wire and feed without pulling everything apart. Now I have a few ideas.

As requested, here are a couple of pics of the car.

Thanks again,
Rick F.

39 Cadillac series 60s
56 Thunderbird

[funnytain]

Ooops, this was suppose to be included. Guess I have a lot to learn............

[joeceretti]

The wire runs over the glove box and up the passenger side pillar. It runs to a door switch on the rear passenger side and also to the pillar switch on the drivers side. These wires are hot (connected to the negative feed) and activating either switch completes the ground.

The first, and worst, problem with mine was exposed wires (failing insulation) that shorted out over top of the glove box and fried part of the wire. I changed out the wire which solved that. The second problem was that both switches were corroded. I used contact cleaner and switched both back and forth. Slowly over a few days I repeated and at this point both switches and the light work fine. I also cleaned the light socket with a small brush and contact cleaner.

[pauldridge]

Rick,

I'll assume your setup may be similar to my '40 60 Special.  I had the headliner replaced recently and was able to muck about with that $$%^&& Dome light setup.  The wiring does run from the dash, up the driver side A pillar, then along the roof line just over the door openings to that switch on the driver B pillar post.  The original wiring had the dome light grounded at its mounting (it attaches to a wood base, so it seems like there was a ground wire going to solid metal.

I wanted to have door switches on all my doors, so I decided to switch the whole setup over to a constant-available power at the dome light, with each of the switches (including pillar switch) providing the ground.  This is pretty easy since, as I mentioned, the dome light base screws into a wood substrate, so it is isolated to ground.

of course, this would be nigh-on impossible to do without pulling down the headliner, or at least at the areas near each B pillar.

Hope this helps

phil auldridge
Austin

[funnytain]

Thanks for the help !! With the info I found where the wires go and fixed the problem. I traced power to the light and it was actually a bad socket at the light. I fixed that and found the door switch which I was totally unaware of. The car was painted years ago before I had it and it was painted the car color and not visible. I have only one door switch at the passenger side rear door as well as the post switch. Seems strange but that was 75 years ago thinking. All works well now.

Thanks again to all!!

Rick
39 Cadillac Series 60S
56 Thunderbird

[joeceretti]

Great to hear you have it working. Just for my general knowledge, does the wire on your car run up the passenger or the driver side pillar?

Joe

[funnytain]

My wiring goes up the drivers side to the switch and then I assume to the door switch. I ended up using a wire signal tracer to follow it once I new the route, I had a signal all the way to the lamp. The socket bulb spring is loose and I need to tighten it. For now I added a drop of solder to the bulb because the head of the screw holding the dome light to the ceiling is stripped. Now it is a tight fit and works fine. I was thrown off because it was a new bulb and worked fine until one day the battery was dead and I discovered I had left the the switch on but the light was off and it would come on intermitently.

Thanks for the help !!

Rick
1939 Cadillac series 60S  6019S
1956 Thunderbird

[joeceretti]

Thanks for the info in the routing. The Fisher body manual is at once very specific and very vague. First hand knowledge is always the best.