I want to install a dome light in my coupe,and I could use some help.I have a simple on/off switch on pillar and dome light mounted.The light and bulb are double contact,like the T headlight bulbs.I also know where my hot source is coming from,and I know I need a ground. Can someone tell where the wiring goes to and from Thank You
Guess you can do it both ways - either wire the hot cable through the switch and then to one of the contacts on the light and let the ground cable go from the other contact directly to ground - or wire the hot source directly to one contact on the light and let the ground cable go from the other contact first to your switch and then to ground. Electrically the same, your choice
This older post has diagram of the sedan dome light wiring.
http://www.mtfca.com/discus/messages/179374/241715.html
Thanks Dan. The second alternative I described above seems to be the Ford way
If you do it the second way and the switch goes bad and shorts to ground, the light will come on. If you do it the first way and the switch goes bad, you will want a fuse.
Mike,
You don't need a double contact bulb. The headlight bulbs are double because there are two filaments in them and the base acts as a ground, (really a third contact).
If you use a double contact bulb, make sure it only has one filament. That way, only the contacts feed the filament and the base is not connected. OR, have a single contact bulb with the base as the ground connection.
Jerry, It is a one filament bulb.I'm using it because the fixture came that way,and connections are pressed into the fixture body.Too much trouble to swap out. Thanks for everyones input,got it wired last night.
If it's got a single filament bulb with 2 contacts, it means the bulb housing isn't grounded and it has to be series wired. One contact goes to 'hot', the other goes to ground.
It would be smart to make it a 2 wire system anyway. One wire goes from the hot source, through an in-line fuse, to the switch, to the bulb. The other comes from the bulb, following the came course as the hot wire, all the way back to a good ground, like the frame, for instance.
Dennis, That's what I did,except for the fuse part. What size fuse should I use. I do have some in line fuse holders. Thanks,mike
Probably 15 amp max. would be my guess but it really should have a fuse in it and that fuse should be as close to the power source as you can get it. Those wires are running up through cloth and wood. Should they (or the switch) short out, you could burn the car down.
15 amps would be good for at least 90 watts.
Find how many watts the light bulb is and divide by 6 (assuming you are running a 6 volt system) which will give you the amps draw.
thank you all