VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 No ground for dome light

i am diagnosing why my dome light doesn't work. Hot wire goes to the dome light and I have juice there (actually on the ground/socket side of the dome lamp, then wire goes from the contact point of the bulb to the switch on the passenger side B pillar. Then I have an 4 inch wire from the other side of the switch soldered to the metal on the B pillar. The problem is, I have no ground in the B pillar - no continuity between ground and the B pillar metal. There must have been continuity at one point or they would not have soldered the wire there - but now - no ground. What's the best option? Run a whole new wire to a place I get ground, or diagnose why the B pillar has lost ground? Does the B pillar ground to the sill plate with bolts somewhere - maybe mine are corroded? Looking for options.

It always helps to know the year of your car. At any rate, on my 1932 Chevrolet the ground wire runs from the switch on the passenger side B pillar and up the B pillar, along the inside of the roof to the inside metal part of the body over the windshield. The ground wire is soldered to the inside of the body at that point to complete the ground for the dome light.

You can run a ground wire to any place on the body that has a good ground and your dome light should work fine. As you discovered, on the dome light the ground is switched.

Sorry. The car is a 1931 4 dr. Sedan.

The same would be true for the 1931 4-door sedan as well.

My '31 2-door Coach had the switch on pass side rear door post, and a short lead going from switch to a screw which went through body sheetmetal right by the switch at door jamb. Looked to be original.

Isn't your car a Canadian model?

Yes, my car was built in Canada, April 1931. Reason I mentioned method used is it seemd so much simpler approach than running a ground up and over to area above windshield. If any problem developed with dome light, so much easier to trouble shoot.

I agree....but that is how the factory ran the dome light ground wire. I thought that it was weird when I saw the routing of the wire but I have seen other cars the same way.

I ran a new ground wire from the switch to above the windshield, drilling a hole in the mounting bracket for the windshield regulator board and using a small bolt and solderless connector. It fixed the problem. I now have a working dome light. Thanks for the comments. I would recommend to anyone doing a new headliner to run a ground wire before they start in on the headliner if their dome light is not working and it's a ground problem with the pillar. Or, maybe I'm the only one who has seen this happen?

Nope....a bad ground to the dome light is a fairly common problem.

On my restoration because I had no interior in, I ran my dome light ground wire the full length with the positive feed wire down the back of the dash area and connected to a common ground with other wires, i.e., directional flasher ground. I have a ground wire connected to all directly off the chassis ground. Ran another ground wire off the chassis (at the rear, fuel tank sender ground on chassis cross member)to the fuel tank apron sheet metal. This allowed me a better ground to both rear fenders and the tail light brackets/tail lights.

Sounds like an excellent idea to me since these old critters are famous for ground issues.

I realized that when I tried to get my tail lights working and they had bad grounds. Sheet metal nailed to wood, nice fresh paint, and panels not welded to each other just don't have good continuity. The chassis is the logical solid electrical link. I had to grind off some paint under the fasteners but that was all I had to do after I ran the wire from the chassis to one of the fuel tank apron to fender bolts. With the apron grounded, it was the conductor over to the other fender. A little more removal of paint under the fasteners and I was all set. I did use dielectric grease at all those connections to hopefully keep any rusting down and possibly future, poor ground conditions.

You definitely did your homework to eliminate the possibility of any future grounding problems.