Wiring help (1 Viewer)

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Hello I am new to this forum and new to FJ's (I have a 1976). I have already been all over this forum and all are a wealth of knowledge. I am just trying to get my FJ a little more road worthy to drive the family around for a few weeks and then tear it down. I am running into an electrical issue though and I thought maybe a somebody could help me resolve. I have already looked at many schematics but they dont seem to be exactly what i have.

None of my gauges work (with the exception of voltage), no blinkers, no brake lights. So I pulled off my fuse box panel and found a wire coming from what I believe to be the engine fuse and mostly had all the insulation melted from it. There were small pieces left and looked as though it was entirely black with no other markings. So I started tearing into the harness and of course it gets into a very difficult area were i cant pin point which wire is which. This wire has also broken during my troubleshooting and now the truck wont turn over.

Any recommendations or ideas would be greatly appreciated. I would like to figure out where this wire goes and maybe splice I to an easier location.

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Beautiful 40!!

But, your wiring looks really dangerous... all those blue female spade connectors are sloppy. The splices are also sloppy.

I don’t think whomever did this work has a real understanding of just how dangerous this is.

I don’t know ‘76, but I suspect most of those “blue” connectors are circuit-segments that a PO added.

You really need to figure out where these “blue” connections go (trace the wires) and clean it up. I’d replace that part with new... and don’t overlook the “blue” near the firewall.

The wire with no insulation has apparently shorted out and melted the insulation.

Not being familiar with ‘76, I hesitate trying to help you... it’s way too easy to burn your truck to the ground.

Mark (@Coolerman) is the expert and is familiar with most years. He’s not generally online on weekends... be patient and he’ll get back to you. Edit: I’m long retired... I thought today was Saturday!!
 
Joined
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Beautiful 40!!

But, your wiring looks really dangerous... all those blue female spade connectors are sloppy. The splices are also sloppy.

I don’t think whomever did this work has a real understanding of just how dangerous this is.

I don’t know ‘76, but I suspect most of those “blue” connectors are circuit-segments that a PO added.

You really need to figure out where these “blue” connections go (trace the wires) and clean it up. I’d replace that part with new... and don’t overlook the “blue” near the firewall.

The wire with no insulation has apparently shorted out and melted the insulation.

Not being familiar with ‘76, I hesitate trying to help you... it’s way too easy to burn your truck to the ground.

Mark (@Coolerman) is the expert and is familiar with most years. He’s not generally online on weekends... be patient and he’ll get back to you. Edit: I’m long retired... I thought today was Saturday!!
 

BeerM3

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As a fellow '76 owner that had some melted wires when I purchased mine, I'd jump in a time machine and go back and send mine off to Mark referenced above. I "fixed" my front harness (though the hazard still required a cheap workaround because I missed something) with some of his website parts, but I did purchase a new rear harness section from him that was plug-n-play easy and perfectly replaced the hacked up mess that was under there. I don't know if he's taking on work right now but I'd definitely ask. Check the classifieds too. Once in a while a decent harness goes up for sale, although '76 was kind of a transitional year so there can be nuanced differences from a '75 or a '77, etc..
 
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Follow the burned wire( every inch of it ) until you find the issue. Whatever caused the melt may have been corrected or you may find the smoking gun, verify what it goes to, determine that part is ok, replace wire. Just fixing the wire and not knowing what melted it or determining that the wire and what it powers are in good condition could lead to problems.
 
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Thanks everyone for all the great advice. As I continue searching through this harness there are numerous plugs that have no home and wires the are just cut. Also the wire that burnt also melted to other wires causing them to melt in spots compromising their insulation. I think my best bet is to replace the entire harness. Any recommendations are greatly appreciated. I want to keep as stock as possible but I am not against upgrading to more modern electrical system and preferably a plug and play or at least clearly labeled. AThanks again for everyone's input.
 
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I will take it out and see if it is repairable. There are many poor splices and extra wire is hanging and not secure. I have found several things that have made me think that this FJ has been imported from Venezuela. Would the wire harness be the same as the U.S. harness?
 

ToyotaMatt

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I will take it out and see if it is repairable. There are many poor splices and extra wire is hanging and not secure. I have found several things that have made me think that this FJ has been imported from Venezuela. Would the wire harness be the same as the U.S. harness?


hey Jared ,

shoot me a PM here ,

i Have Most of what you Need to Repair the Fuse Box AREA , of your

truck , using ALL OEM TOYOTA Parts , That i will Tripple Inspect and

Verify and in SOLID condition and Good working order ...

I also Carry NEW Reproduction Fuse box holder as well


as just like my Good Friend @Living in the Past mentioned ,

NEVER Think Twice about a Aftermarket wire harness ,

it would be a very Regretful Decision for you shortly after a Install ...... :confused:


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DSRTRDR

I can mangle anything ...
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having installed a Painless harness 15 years ago and not encountering any problems since, I just want to testify it can be done in a way the reproduces the OEM schematic exactly (although I also run a few auxiliary circuits by now)

that said, I can also appreciate the merit of repairing what you have, if anything recognizable is left - there is no better solution than the one that accomplishes what you want to achieve with your truck
 

Dizzy

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These trucks are otherwise circuit-protected except for the alternator, ignition, ammeter, starter, ignition switch and the hot side of the fuseblock, in an OEM configuration with a fusible link at the battery positive.

Post up a pic of the wiring at the battery positive terminal. Does the ignition work?

My guess is that the PO tried to get the always-hot source for the CD player and couldn't find fuse taps at the Autozone three blocks away, but that is just my guess. I'd guess that the problem started between the ignition switch and the fuseblock. I'd map-out what is obviously modified at the fuseblock, then inspect the wires going to the ignition switch. Also, look at the battery positive for the white/light purple, and at the alternator. If things look funny, then pull the main harness (after connections have been identified) and inspect the entire length of the fat white/light purple wires and white that run thru the fat wiring loom. But, if they look good, then you could inspect from the alternator and fusible link for continuity to proper fuse block locations and make sure that the ignition switch turns on the proper locations at the fuseblock (by measuring for continuity only, no battery hooked up).

By the way, there is clearly insulation missing from one of those spray painted wires in the first pic, it might be mouse damage.
 
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These trucks are otherwise circuit-protected except for the alternator, ignition, ammeter, starter, ignition switch and the hot side of the fuseblock, in an OEM configuration with a fusible link at the battery positive.

Post up a pic of the wiring at the battery positive terminal. Does the ignition work?

My guess is that the PO tried to get the always-hot source for the CD player and couldn't find fuse taps at the Autozone three blocks away, but that is just my guess. I'd guess that the problem started between the ignition switch and the fuseblock. I'd map-out what is obviously modified at the fuseblock, then inspect the wires going to the ignition switch. Also, look at the battery positive for the white/light purple, and at the alternator. If things look funny, then pull the main harness (after connections have been identified) and inspect the entire length of the fat white/light purple wires and white that run thru the fat wiring loom. But, if they look good, then you could inspect from the alternator and fusible link for continuity to proper fuse block locations and make sure that the ignition switch turns on the proper locations at the fuseblock (by measuring for continuity only, no battery hooked up).

By the way, there is clearly insulation missing from one of those spray painted wires in the first pic, it might be mouse damage.

I am out of town right now but will take a pic as soon as get back but, if my memory serves me right I didnt see a fusable link. Also, the wiring going to the alternator is a mess. Not really sure what is going on with harness especially on the LH side it almost seems like there is some random harness spliced in to it and there is a plug that doesnt look like it could go to anything or even time period correct. Thanks to everyone for their help on this.
 
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I am back in town. I hope everyone had a great holiday. Attached are pictures of wires I am dealing with under the hood. They are going from both the RH and LH sides. Still planning on pulling the entire harness to see if I can fix it.

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Dizzy

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Well, nothing that I have not seen or dealt with before. My first 40 came with a Doorman wiring harness from Home Depot.
 

Dizzy

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Install a fire extinguisher.

Let's get started. Identify anything that looks damaged, and tell us where it goes. Use scotch brite or fine sand paper to identify the wire colors where they have been painted, masking tape/sharpie id tag the wires.

Pull the big battery to engine lead and battery to starter lead, the starter to frame, clean everything, and don't hook up the negative battery terminal. I use those post covers that come with new batteries for when I'm performing anything that might short out. I leave the negative off at all times, except when I need it. Be aware of the exposed positive sources at the starter, alternator and coil/igniter, they will spark when a tool touches them that is touching the rest of the truck. The battery positive terminal looks so dirty that it may have stalled the truck. There should be no wiring at the positive terminal aside from the black fusible link, so pull all of it, and identify its installed position, unless it is connected to a big white (that goes to the ammeter). Your going to need a fusible link right away, but you might use an in-line fuse until you get some things determined.

I still don't know where that fried wire at the fuse block goes, or even what it is hooked up to. I'm not actually going to dismantle my truck to find out, but you can tell us by measuring for conductivity with a multimeter. Pull all the fuses, aside from the 'engine' fuse, after you record their location; determine if any fuses are blown with a flashlight. There is a top and a bottom to the fuse block, and a cover with writing. Then with the battery disconnected, and the posts covered, let's see if we can get conductivity to the starter terminal from the ignition switch at the 'on' position via the White that is attached to the battery positive terminal via the fusible link. Also, make sure that there is no conductivity to the engine, body, or frame.

You get the idea, right? If it makes sense that you test circuits with conductivity and the logic of their layout in the factory wiring diagram, then we can do the ignition coil, distributor, and fuel cut solenoid at the carb, and then work on the alternator and voltage regulator (driver firewall). If it all jives, then then engine should be able to start with this simple circuit and one fuse installed.

Obviously, there are going to be good and bad techniques for running wires. Also, I'm running more than the factory configuration for grounds, primarily for lights. There are good ways of stripping wire, decent connections, etc. I use a combination of self-vulcanizing and sticky electrical tape. Etc.

I hope this is not difficult project, but I hope that there are no sketchy shortcuts taken.
 
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Thanks for all the great advice I will start digging in hopefully within the next couple days. I am also concerned of what wiring has been done and the amount of damage that has been done by the burnt wire. I will pull everything and inform what i find. I know I am going to have many questions as to what is right and wrong due to the many splices and cut wires. Thanks for everyone's help. It great to be involved in such a great forum.
 

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