Dome light question

[vintageman]

Alright this is probably a stupid question and I am probably overthinking everything but here goes. I installed a one piece TMI headliner a couple years ago and really like it, I am now getting around to the last few things like installing my dome light. I have run a new dome light power wire from the drivers side harness and it is coming down through the headliner to connect it to the light housing. Does it matter which mounting screw the power wire connects to? There are 2 "lugs" that connect to the bulb, so I figure either would work for the power connection but wanted to ask first. Also, if using the mounting screw to connect the power wire, won't this also ground out the power wire? The new dome light is a Scott Drake product if that makes a difference. Pic is below, not my pic, just one I found that looks like my new dome light. Thanks.

Tom

 

[Don C]

You are correct. If both of those screws go into metal in the dome light bracket they will both be grounded.
Maybe the other two holes are for mounting.

 

[vintageman]

Thanks Don, the dome light assembly is plastic with only those 2 strips of metal. As I understand it, the threaded retainers in the actual roof are metal, so if using screws to mount the power wire to one of the metal strips on the dome light assembly, then I would be essentially connecting the power wire to the metal roof and cause an electrical short. That doesn't sound like a good thing, so how does the power wire connect to the dome light assembly correctly?

 

[Richie]

I had the same problem with my 72, I though I had the wire hooked the right way. As time went on, the battery went dead, I charged the battery up, and later it went dead again. I put a new battery in this time thinking maybe I had a bad battery. not to long that battery went dead, So I took my car down to the Auto electric company in my home town, inform them my problem, left the car there and went home .The next morning they called me to come get my car.When I got there I ask them what was the problem. I was told the dome light was cross wired that I had the power wire grounded.

 

[vintageman]

Thanks for the response Richie. So did they shorten the power mounting screw so that it only made contact with the dome light metal strip and not get screwed into the actual roof or did they correct the issue another way? Thanks for your response.

Tom

 

[Richie]

I can't answer that question They fix the problem, and I never mess with it sorry.

 

[vintageman]

Thanks for the quick response, I think that I will try a shorter screw for the power wire and see how that goes. More to follow.

Tom

 

[Cjmach1]

As far as I can remember it’s one wire live and a screw grounds the base to the sheet metal

 

[lectricegg]

I would remove the bulb and mount it without the wire connected. Check each screw to ground with an ohm meter or continuity light. Hopefully only 1 of them shows a ground.

 

[BFH 429]

Vintageman - I know exactly what you are talking about. I, too, bought the same SD dome light and I can't for the life of me figure out how the heck they expect this to work the way they delivered it. It's a guaranteed short circuit if you install it as is. A shorter screw isn't a bad idea, but I'm not sure I would trust that. I'm thinking about cutting the metal leg off one end (that goes around one of the screws) and soldering or clipping the hot wire to the lead that's left. The other side can stay captured by the screw to ground the system and complete the circuit. Only other thing I can think of is using a plastic screw on that hot side, or a plastic push pin connector of some sort. What did you end up doing and did it work?

Marc

 

[vintageman]

Marc, I ended up using only 3 mounting screws and brought the power wire down through the dome light assembly and mounting it to the inside of the light to the power leg terminal. It was definitely a pain but at least there is no short to ground now and the light works. Good luck Marc and I hope this helps. Let me know if you have any other questions.

Tom