I have trailer with a short in the marker lights -somewhere- between the plug and the 15 lights that run off that circuit. So far I've figured out they didn't believe in grommets and the light bases are riveted to the trailer. Before i start breaking -more- plastic light bases and digging for a rivet cutter, is there a trick i don't know about for localizing shorts?
Jump power to running light wire with no fuse and look for the magic smoke , seriously if there are no junction boxes to at least isolate some of the lights it is tough, especially if the wire is run inside of a tube. Usually anyplace it can move in any hinge points is the first place to look, usually I just rely on getting lucky eventually. I hope someone has a better answer because I am curious as well.
That was my Dad's first suggestion too, unfortunately he was serious. I think i found the issue, i'll find out tomorrow.
A thermal imaging camera would make it easier. Even a non contact thermometer might help. Run a load with the shorted wire as your ground, so it's carrying as much amps as it should. If it's grounded good enough that the shorted wire has a low voltage with this load then hopefully the lights won't draw enough amps, so that the wire will only heat up to the short, and not to the lights. If you have a regulated power supply (a big solar panel would do it) that you could leave hooked up with a horn/alarm wired with that wire as the hot. Then you go through the wiring wiggling as you go, when you disconnect the short, the voltage goes up and the horn sounds.
Are you blowing fuses/circuit breaker, or are the lights just going out? Bad splice or bad ground is typical.
I have two set-ups one with male one with female plug and sockets 7 wire with flashers wired in. I just use a 12v battery to separate from truck or tractor. I use a multi meter to check voltage. I like to start at the front and work my way back checking voltage as I go. But I have hooked it up and looked for smoke no joke, especially this time of year with all the mud and grim under a trailer. But first I would check all grounds. Truck Shop
I have found one of these to be really handy finding shorts and tracing wires within wire looms. Simply hook the box part to the plug end, follow the tracer until the tone disappears, there's your short. Really nice where there's 15 wire's together in a loom. No smoke, no blown breakers. https://www.amazon.com/Sperry-Instr...d=1485911325&sr=8-4&keywords=wire+tracer+tone
I put this together last year to deal with the newer trucks that don't have fuses for the trailer wiring. I have several of these little batteries for deer feeders. Positive wire has an inline fuse holder and then disconnects that can power clearance lights, right turn, or left turn. There was one light base with an abraded wire where it went through the side of the trailer.
Crane operator, does that tracer work well? Even if wires are bundled up in loom tape, does it work if it's not right up to and touching the powered up wire? Looks like a great tool, if it has enough power. Cheers, John
Power the circuit through a headlamp and follow it to the short with an amp clamp, takes less than 5 minutes to find the short usually. If you don't have an amp clamp you can do the "wiggle test" and watch for the light to go out.
John Shipp- The locator/ tone part (looks like a pencil) has a adjustable distance/ sensitivity for locating. You can hook the sender portion to a wire in a fuse panel/ cab, and find what loom its in 15' away, adjust the distance/sensitivity level way down, and then identify which wire in the loom is the one your hooked to in the cab/ fuse panel. It doesn't have to be right on the wire in a loom, if you have the sensitivity turned up, it will light it up/ tone, 2' away from the wire. If the sensitivity is way down, you'll have to be right on the wire. It adjusts by a thumb wheel right on the pencil part. Its a great little tool. If the wire is broken somewhere in the loom, or at a connection, it will only generate tone up to that connection, then stop.
Sounds like excellent tool. If wire is not broke, only shorting, does it change tone at all when going past the short? Thanks, John. Lots of good tips in this thread, electric shorts and breaks often give me headaches!!
"Power Probe" is another real good one.. watch the video..
From what I gather from the PP video, it has its own power source and powers the wire.. you take the "pencil" and run it along the suspect wire until the tone/light shuts off.. That would be great if you had a "fuseable link" in a wire and no wiring diagram to identify it.. Kubota, JD and Yanmar started using them at the starter wire.. it looks like a regular old wire w/ a slight bulge in it to hold the link and ofcourse its in a loom.. You'd look right past it if you didn't know what it was.
I have the power probe 3000 intelligent circuit tracer, paid $115.24 for it from Tool discounter.com Got to use it on a Volvo A40D to find a short, it worked really well. the bad spot was in a small bundle harness that ran behind the engine about cylinder head high. And found it pretty quick, the actual repair took longer because it was in a very confined space. That's when I realized, that was 115 well spent.
Problem with the smoke method is that it always seems to burn the insulation off the entire wire if it happens to be shorted to ground
3406, your comment reminds me of the time I had to replace alt. on a pc490 hoe. not very handy to get to, lay over top of the engine to get to it, while working in a dark hole. The + & - wires being of the same size and color, I glanced at them to get a mental pic how the wires looked, instead of going and marking them. Yes, you guessed it, I hooked the + straight to ground and sent 24V to it and wondered why the engine wouldn't crank. Looked back at the engine compartment cause the operator was hooping and hollering, it looked like some one had lite 20 smoke bombs back there. Mean while I was telling my self, you dumb ***, a simple alt. replacement job, just turned in to a full day of changing out a engine wiring harness. So after the smoke cleared, I looked, and said thank you God! I'm in luck, the + wire was a single wire all by its self and went straight to the hot side on the starter, and no other damage! When I told the operator that, he says WOW! I didn't know that just one wire could put off that much smoke!
We had a guy do that at our shop last winter. Guess he forgot to hook the hot wire from the starter back onto the alternator and left it touching the block.
Crane op, I just ordered one of these. Had a few chaffed or broken wires recently, hoping this helps with finding the broken ones.
Looks similar to the one in your link. Will post something here once I get chance to try it.
We had a little incident with our 70 ton crane, the driveline hooked the wire loom that comes from the upper swivel in my 70 ton crane, and removed all the wiring from upstairs by ripping it all out. The locator was a life saver on that little project for finding which wires went to what, and I found two wires that were broke within the loom also. Between it and a simple 12v light tester, we got it back together, but it was no fun at all. The crane has full gauges upstairs, start stop ignition, and full outrigger controls. Probably like 70 wires altogether. This was one of the looms laying on the ground after the driveline hooked it. All the outrigger control wires are white, no number markings. The one you show in pictures is just like mine.
Oh my! Nightmare.
We were about a hour away from home, were moving the crane around on the jobsite this spring when it happened. I still had the detroit running, and told them we were done running crane that day. I tied up the remnants of the loom, and slid the crane into gear and motored home. We did a few work arounds and had it on a job the next week, but I didn't get all the upper stuff back working until late this summer when I had some extra time.
One of the "to do" projects that get thought about almost every day for months, glad to hear you got it beat. Gives me confidence in this gadget! Do you use a couple of extra lengths of wire on the transmitter, or clip it close up and turn the sensitivity way down? I notice the tracer pen beeps when anywhere near the transmitter.
I've never used extra wires on the transmitter, I've only just turned sensitivity up and down. Most of the time, I don't have the sender really close to the broken wire, its usually 5-10' away looking for where a wire goes in a loom. You can turn the sensitivity way down, and actually point out a wire almost in a group of 5 or 6, then use a continuity tester or a test light to be sure you have the right one.
the power probe sends a 400 hz sqarewave signal down the wire and this is what the signal tracer picks up