Electrical wiring nightmare

Ok to be upfront, I'm no expert electrician by any means, but can manage to work at it long enough to eventually figure it out, but now am looking for a much faster way to go about it is the jest of this thread.

Years ago now I bought a used machine, a pretty simple machine really, no computers, all mechanical everything, simple gauges, starter circuit, gauges and instruments are basic at best, but someone has been butchering the wiring harness over the years, cut it apart and spliced different color wires into it, taking things off like sensors and some gauges and basically butchered it so badly, now its time to start over and make a whole new harness, put new sensors on, put new gauges in, it needs a new cab blower motor, the glow plug isn't working, that needs to replaced, simple things.

Which brings about the question of the day, whats the best testing tool to use to find out where wires go, where they are dead, where they are shorted together and the largest thing is this, with absolutely no wiring diagram to go by that is accurate. We're finding out the harness has in the past been hacked, patched, rewired, butchered and cut up so badly, nothing matches anything anymore, seems everyone who's come along has used whatever they had at hand to get it fixed, now I have three different colored wires all hooked to one wire throughout the harness, so a red on one end, is supposed to follow through to red on the other end, only its red on one end, turns blue somewhere in the middle and ends up green on the far end................................or changes colors a half dozen times throughout the harness and also changes wire sizes along the way.

I know in the right hands, someone could figure this out in a few days, but myself, its taking forever, so the plan thus far is to track the harness one wire at a time, label them with numbers, draw up a wiring diagram, then the plan is to remove the whole harness and make up a new harness that matches a new made up wiring diagram we have to make ourselves with wire numbers already on them and put the whole thing back together again since no harness is available from anyone I can find anywhere, I've spent about a week working off and on and have about 1/4 of the harness tacked down and labeled. We've been so far not trying to make things worse by taking the whole machine apart at one time and some of the harness isn't viable unless we do.

I've been looking online and they make short or broken wire testers?? that can track wires through a harness to find a bad spot, never used them, do they work, what is something worth getting that's simple enough any idiot can run, I don't need to test electronic fuel injectors, pulse anything, have graph displays and etc, just needing something basic to help me out, all I've ever used is a multi meter. Thanks for any help in advance.

The Power probe 2 has changed my view on electrical problems. You can hook up to the machine's battery and apply either machine power or machine ground to a wire or unit. It also tells voltage and if wire is grounded or hot. There is no magic involved, still requires quite a bit of head scratching and wire chasing. But is one more tool in the shed to use. Good luck!

Power probe and a digital volt meter is what you need. I usually get by just using a digital meter. But the power probe comes in handy for testing. You can send voltage or ground with it and test continuity ( although I prefer my meter for that.) It's also handy to have a assortment of harness connectors for testing, but that comes from years of collecting. It may not be this way for you, but your project sounds fun to me. I love those types of projects.

You can also by the power probe with a signal generator so that you can scan over the harness looking for a open circuit that is unseen.

You need what is called a time domain reflectometer but they are in no way cheap. They will find wires that are broken from a few inches, to several miles in distance.

Best thing to do is get an electrical print of your machine from most likely a service manual and start "ringing" wires from end to end. This means checking for continuity of the conductor(s), (wires). It is about the only inexpensive or affordable way to do this besides visual interpretation.

Wire color means nothing to me so point to point measurements are necessary.

Look into a 'Tone Generator'. It sends a signal through the wire that you can follow with the probe and find where wires go even in a loomed harness. I picked up the Fluke Pro3000 model on ebay for $50, but there are plenty of brands and options.

Tone generators are very helpful. I also use a power probe and a DMM with loadpro leads and back probes so I don't have to take apart connections.

This is the broken wire finder/ tracer that I use. $40.00 to your door. Hook the "base" unit up to the wire you want to trace, and the locater will follow along through the loom until the wire is broken, or you can find the good wire at the other end of the machine. The "locater" has a dial which changes sensitivity.

https://www.amazon.com/Sperry-Instruments-ET64220-Installers-Must-Have/dp/B00279JLBQ

Just because I'm curious, what are you rewiring? Tile machine? Just trying to get a idea of how many wires and how long to make your new loom.

I like the the 3m tape numbers for identifying wires, if you don't have to pull through a swivel.

https://www.amazon.com/Wire-Marker-Tape-Dispenser/dp/B00OI737OM?th=1

One of the trenchers is next on the list, that is a one off machine custom built, so there is absolutely no wiring diagram to had for that, since the cab was an aftermarket new cab, then the ac and heat were installed, also aftermarket units, not to mention the engine and laser electronics were never around when the machine was put together, but before we get that deep into that technical of a machine, we're starting out really simple, this unit in the shop now is a feller buncher made overseas back in the 80's and then pretty much discontinued for support anyhow. I have a very vague wiring diagram, or part of one anyway and the rest is just a guess at this point. For as simple as it is, this whole project shouldn't be that hard or time consuming, but minutes turn into hours and hours into days with little to show for my time it seems.

I'd cut it all out and start over new, but then I'd have to start from scratch, wire it up and string everything for length, hook it all up, feed it through everything and get it all up to snuff then take it all back out, put it in a wiring harness so to speak, then feed it back through everywhere it needs to be fed through and hook it all back up again. It might get down to that in the end, but I was just trying to piece it all back together first, hook things up and replace the components that need replacing, then take the harness out, lay it out on the shop floor, measure it all up, lay all new wires out to length, mark them all, put it a harness, then feed it through once and hook it all up once was my original thought.

This afternoon that whole concept was looking pretty bleak and that idea of just cut it all out and start over was really tempting.

I know most of you guys have far more experience with wiring and electronics than I do. Thanks for all the suggestions, one good thing about this whole ordeal, I get to buy some more toys to play with, testers and things, so thanks for the suggestions and information. I now need to study all the things you guys have posted here and figure out how to use them and what will work best for each issue I'm dealing with, heck for that matter, I might just start ordering them all and figure them out as they show up at my door.

I've got a old crane that I keep telling myself that we are going to rewire, because its a cobbled up mess, that I have only added to. I think a guy could get a good start on a system by buying a 21 or 28 circuit system from painless. All the hot rodding guys just install it and it saves a bunch of work. I haven't with the crane, because you have to do it all twice on it, once upstairs and once downstairs, and it all has to go through the swivel too, and I'm just too busy to do it for a old crane.

Anyways, the "painless" set up gets you all the typical gauges (water, oil pressure, tach, volts), a ignition set up, and then because its "car" you get turn signals, head lights, wipers, etc. I don't know how much extra controls you need to run electric, but you might just take a look and see if you think you could make something like this work.

https://www.painlessperformance.com/wc/20104

https://www.painlessperformance.com/wc/10102

The 21 circuit is only $250 and I could see it saving a bunch of time. I would maybe call their tech support, and see how long the wiring is, and if that would be long enough to work in the feller buncher.

I have the power probe with the signal generator. It works well overall. Other less expensive options have been listed. I have had it not work well but in a large harness with 40 + wires it did not. Cut the insulation off in the middle and then it would read when powered from one end but not the other. Ran one wire from there to the dead side harness connector.
Have done a fair amount of that type stuff. Like to start by putting the harness back as original and go from there. If it is real bad, like an old loader that caught on fire with cotton gen trash, cut it out and make your own harness from scratch. Those new high tech machines usually just have to have a harness.
Good luck and keep us posted please.

The installation PDF that painless provides with a harness is pretty walk through step by step.

https://www.painlessperformance.com/Manuals/10102.pdf

Your doing it like I would have to. One wire at a time and placed on a diagram.

My only suggestion, when you are ready to make the new wiring harness, get control cabinet style wire of the gauge appropriate for the load. This wire is very flexible and will take vibration much better than wiring like THHN.
I wish I had a brand or wire type to give you. Memory is shot. Maybe Carol wire ( brand and probably not spelled correct ).

Good luck.

On one project in the past, we installed a diesel power unit and to wire everything up, we used trailer wire that comes in 7 wires in one coating, when we'd need say 17 wires run, we'd run three of those lines, mark the cables and the wires in each cable then have spare unused wires in each cable for later use. For heavier loads, we'd also run individual larger wires and then zip tie the whole thing together as we went, it did work really good in fact, that machine has been in use now for almost 20 years and we've never had an issue with it. I'm seriously thinking about the same method this time around once we figure out exactly what we're dealing with, and for the larger alternator wire to the starter and dash, just to run a single larger wire and zip tie it to either one or two sets of trailer wires, depending on how many individual wires we need. I had actually forgotten all about that until my wife asked how we wired that up all those years ago...............guess too much stuff in the past to remember it all now.

I've been using the wire number stickers like is used in electric motors to number all the wires, once we run out of the numbers, then we doubled them up, say the numbers went to 15 and we'd need more, then a 6 and a 1 sticker to make 16 and so on for each end, I think that's how we did the power unit years ago, the cables were letters then numbers on the individual wires and made up the diagram as we went, once done we photocopied the diagram and then laminated one or two copies and miniature of the diagram and laminated that and taped it inside the cover of the control box so one was with the machine at all times, also made it moisture proof so to speak.

About the ONLY sane method to replace a badly butchered harness is to label EVERY wire END dash or sender then pull the entire mess and build NEW sitting both to a piece of plywood table top. Identify the wires ONE AT A TIME cut them out ONE AT A TIME for a measurement then install a New ONE piece wire with new ends until achieve a full harness. Build your Own Color Coded Diagram as set it up.

I've been pretty lucky in my career to only have had to mess with a couple of burn jobs where the harness has to be repaired as the part number of a new harness could not be verified. It became obvious on those projects that it was easier to just pull the harness out of the machine and do the work on the floor or a bench if possible. There is no good way to piece them back together, they take a ton of time, problems after the repair are still pretty likely if you have electronics and customers whine loudly about the costs.

I'm working on a video for harnesses right now and one of my clients donated a butchered cab harness out of a wheel loader. I should have the program finished some time next week. Just a show and tell on this one.

Actually at least for me it's easier to build and install new wiring harness than repair one. It just takes time
and patience. I used a EZ harness below and still only used half of it, mainly for the standard items like
headlights. The chassis harness I made. Have a plan and work it. When removing a cab harness remove it
with switches plugged in makes it a lot easier. I have moved a complete 2005 KW cab harness from one cab to
another including power distribution box in 8 hrs.