SanTan Devil

So, I just about got every fuse and bulb delivered in the mail today. I quickly replaced the back up bulbs and the entire license plate assembly (with bulb)... and no dice. Any ideas where to look for a short in the system? Or, otherwise troubleshooting suggestions?

Note: I have the trunk light assembly disconnected. Probably should not matter in regards to the aforementioned non-working lights but, I'm in the market for a new assembly (as there's a broken piece of copper surrounding the bulb) and hope to find one at a swap meet I'm attending this weekend. Or, prove to my wife that the few I've found on eBay are a deal, should buy.

oldcutlass

First what year and model is your car? Second, do the tail lights work? If they do, your issue is somewhere between the license plate light and the right tail light.

SanTan Devil

Sorry, forgot to mention I have a 1972 Cutlass Supreme Convertible. Yes, the tail lights work. Thanks for helping me isolate the area.

Vintage Chief

Test your wire and sockets >>> https://www.harborfreight.com/6-12-v...ster-4288.html

SanTan Devil

I was thinking of testing the wire and sockets, just have to figure out my voltage checker tool. The one suggested above looks far simpler and to the point. Might see if my local Harbor Freight or hardware store has one in-stock.

Also, I was looking and another thing came to mind, the license plate light assembly looks to have a nut for a ground wire but, I do not see a ground wire attached. I can check my 1972 Cutlass assembly manual and perhaps figure if there's supposed to be one. Maybe that's an issue with the License Plate light but, doesn't possibly explain the back up lights. On a related note, I bought a generic back up light socket and noticed that had a ground wire but, I do not see a ground on either of those assemblies.

Thanks to everyone for the input and help.

Vintage Chief

"Generally" speaking, an automotive light assembly will use the bulb socket (or entire assembly) attachment point as the ground. IOW, the socket is attached to the chassis and effectively is already grounded via the attachment point at the chassis & another ground is not required. This of course depends on the location of the bulb socket and/or assembly.
Regarding usage of the test light probe. It is far simpler to check for either voltage or ground using a test light probe. The extremely fine tip on the probe allows you to stab the wire in question anywhere along the length of the wire itself. The probe light will light when 12V is detected. There is a single wire lead. Attach the wire lead to a known good ground (a solid piece of metal), stab the wire w/ the probe and the light will light if 12V is detected - very fast & simple. Save yourself a headache.

Vintage Chief

BTW, many ‘generic’ bulb sockets contain a ground wire depending on type you purchased. All depends on application. You may have purchased a socket which is the incorrect type. Many sold w/ & w/o a ground wire.

oldcutlass

Meant to ask if your brake and hazard lights were working last night? Trunk light is on the courtesy circuit and not part of your issue.