I've got a dandy going here that has me shaking my head and laughing/crying.
Last week I bought an older 12 ft MirroCraft tin boat with 15 hp outboard, sitting on an older trailer. Basically sound and can be used as is....almost...but there are a few things I've been working on. As expected, lights on trailer were u/s, so tossed 'em and bought a cheap kit online that has both tail lights, both marker lights and about 25 ft of 4 strand wire with 4 pole plugs.
Late yesterday, I re-wired the trailer and mounted the lights. Lights wouldn't come on, so figured with all the rust and layers of paint I wasn't getting a good ground - the usual cause.
I drilled and tapped holes by each light and ran separate grounds to each one, then checked ground from car to car plug and showed power at all 3 terminals with a 12V test light. Plugged in trailer and no lights.
I clipped the ground alligator clip to my new main ground on trailer, then poked the needle tip thru the insulation on each brown (tail light) wire and the yellow and green turn signal wires.....this is on the trailer side about a foot downstream of the plugs at hitch.
All showed power at the test light.....but still no lights on trailer - on the far end of the same wires. Went down to each light individually, clipped to ground and probed thru the insulation. Nothing on any of them. HTH can this be ?? I've wired a lot of trailers.....and lots of other stuff, too, and when you have an unbroken wire with power at one end, then there will be power at the other end, too, right ?? Hah.
I walked away from it for a while, then went back with a clear head and fresh viewpoint. No change. I don't know WTH to think. Can't be the bulbs (these are cheapie non-LED) cause no power is showing where wires enter lights but power is showing at other end of wires. Aaaarrggh ! ! !
My job in the USAF was an electronic trouble shooter. i did not do repair work but just found problems and then called up one of the various repair units depending on the type of problem I found. (Micro Wave, crypto, teletype, telephone, German landline, IBM computers, and one more i can't think of). Several decades later at my house, AT&T could not figure out why i could not get reliable computer service and told me the problem was inside my house;s wiring and not their problem. I finally took a strong 8 X magnifier to inspect the copper wires where a tech had used an insulation stripper and found hairline cracks in the copper strands. The tech standing behind me told me they were not allowed to use wire strippers, but i told him someone did and cracked the copper strands just enough to cause problems. When the offending wire tip was cut off and reconnected the problem that had stumped several AT&T technicians was solved. These cracks did not show up in continuity testing, but were causing problems as time went on, no doubt to an increase in resistance.
So repeat the connections and use minimum pressure while stripping off the insulation. Or replace the entire wire.
A wire broken inside the insulation is unlikely with this stuff but possible. 4 wires all broken from the factory inside the insulation.....uh.....??
Haha......it's gotta be something simple, but I've brain far.t.ed myself into mental paralysis. Like I said above - I'll take a couple of pics in the morning. Maybe a fresh look will help, too.
“Everyone behaves badly--given the chance.”
― Ernest Hemingway
i have seen defective wires like you describe,,,,rare but possible. One rat or mouse chewing on the flat wire could let in moisture and you might not even see the punctures. Or the wire was stretched in production and the copper strands were broken. I would use marine wire and dump the flat four wire.
Not a long journey for me on the other. 😢
Cut off the ends.
Use those to wire your trailer lights.
Relying on the trailer as a ground is asking for trouble.