Trailer Ground Problem

[Roger Ski Gapinski]

I have a 4’x8’ utility trailer that I just replaced lights and wiring. Hooked it up to my car and no lights.
Upon investigation I found no continuity on both sides of trailer frame. I spot checked the passenger side by scraping down to metal and checked resistance. This is a collapsible trailer from Northern Tool (20 years ago). No continuity between ground on tongue to main frame so I ran a separate wire to the marker light from ground on tongue. Passenger and marker lights work.
I tested for continuity on driver’s side and repeated the process of running a separate wire to the market light. Market light works but nothing else.
When testing driver’s side frame there is no continuity from one side of tire to the other. This is really strange since it is one piece of metal. I did scrape down to bare metal. If I can’t figure this out I will run a separate wire all the way back to the lights. But I prefer not to do this and use the actual trailer frame as the ground.
Has anyone ever come across this and solved it? Please share!
Thanks so much and look forward to replies.

 

[haknslash]

You have a rusty trailer and rusty metal is a poor conductor.

 

[Roger Ski Gapinski]

You have a rusty trailer and rusty metal is a poor conductor.

I scraped the trailer down to bare metal. I have power to light and good ground. New light still does not work. I will remove tomorrow and inspect. I have the old one that worked and will try it. Maybe the new light is broken inside.
Thanks for your reply.

 

[haknslash]

Is it dual filament bulb? Check and see if filaments are broken.

 

[Roger Ski Gapinski]

Is it dual filament bulb? Check and see if filaments are broken.

Already did. Both good.

 

[Babin Farms]

Make sure the fixture itself is grounded good.

Also, get rid of the snap-loc connectors and either solder & heat shrink or butt connectors with heat shrink to seal up connections from corrosion.

 

[Roger Ski Gapinski]

Success! Since the utility trailer is collapsible there are three sections to the frame. 20 years ago when it was new the bolts that held the sections together shared raw metal. Over the years corrosion has taken its toll!
By connecting each section with wire I was able to provide continuity from the ball and plug harness all the way to the rear lights. All lights work great. Thanks for the helpful responses.
All the best!

 

[Murf'n'surf]

Is it too late for a you've got rusty balls comment?