So I let the factory smoke out of my wire harness

[ken_79-fj40]

It looks like the white/blue strip lead from the battery to I think the fuse box ( I honestly didn't even look at the wiring diagram when I saw the carnage) shorted out somewhere, and it took a bunch of surrounding wires with it. This actually happened when I wasn't around. Drove the truck around a bit wednesday night while doing some jet swapping/tuning on the Weber carb and all was well. Went to start it Friday morning and absolutely nothing happened when I turned the key. No lights, no power to anything. So I pulled the negative terminal off the battery and drove my Tacoma to work. Got home friday night and at about 9:30 I went down to the garage and found this:

Always nice to have something like this happen 6-700 miles after an engine rebuild. So now I guess I find out first hand just how much of a pain in the butt it is to wire up a universal harness. I have contemplated trying to find a used harness, but I think in the end I would be better off with new stuff. Fortunately none of the plugs melted.

 

[Coolerman]

Bummer... Can you tell what shorted out and where? Might help someone avoid this in the future...

Never understood Toyota not fusing the charge circuit or the ignition for that matter. I'm adding those to my restored harness...

Good luck and post up anymore info you find on the cause.

 

[Pin_Head]

The fusible link is supposed to prevent that kind of stuff. Maybe someone removed it or it is the wrong one? Judging from the wire, a failed diode in the alternator probably caused it. Toyota used a fusible link on the alternator wire also on later cruisers ('79 and up?).

Even with the damage, I would repair your existing harness. You have a lot of good wires left. It is easier and cheaper and it will plug right in.

 

[ken_79-fj40]

Pinhead is right on the money. The fusible links are in fact gone. When I first bought the truck like 8-10 years ago they both went up in smoke a day or two after I got the truck. Stupid me I just made a few leads out of some 8 gauge power cable I had laying around and everything worked fine without touching anything else. Then about 2 months later I went to start it one day and all of a sudden smoke came pouring out of the top of the dash. The hood was already open so I jumped out and yanked off a battery cable. It was this same white/blue stripe lead that went up in smoke right at the connection by the firewall. So I pulled the entire dash section of the harness and visually checked it all over to see if I could find any issues. Didn't see anything so I fixed about 6" of harness and put it back in. I had the entire harness out of the truck when I did the full ground up cosmetic rebuild the following year and again I looked it all over and didn't see anything obvious. When this lit up this time I was not around. I drove it 2 days before and all was fine and came back to have no power at all. I find it interesting that you mentioned the alternator. The ammeter in this truck has never worked, and a few years back I noticed it wasn't charging (after driving home with really dim lights one night) but I had about 14 volts coming off the alternator. So I ran a piece of 8 gauge from the post off the alternator to the positive battery terminal and all was OK. Until now at least. I honestly have been meaning to clean up the wiring in this truck for quite a while. Now's my chance, although it's horrible timing. Perhaps I will pull all the tape off and get a few cans of electrical parts cleaner before I spring for a new harness. I would much rather not spend the rest of my summer weekends in the garage.

So now that I think about it some more Pinhead probably is really right on the money. If the alternator were bad that would explain the fusible links burning up years ago. It would also explain the short that occurred further up the harness shortly thereafter, and the lead from the alternator to the harness failing a few years back. Replacing everything with 8 gauge just made the actual harness act as the fusible link.

 

[joeyg1973]

Hmm maybe you want to try a pricey but very cool option and be a guinie pig for us?

ISIS Intelligent Multiplex System - Automotive Wiring Harnesses, Car Wire Harness, Engine Wiring Harness, Auto Wiring Harness, Truck Wiring Harness, Car Wiring Kits

 

[lostmarbles]

Sounds like you're actually very lucky here.

Your whole cruiser could have gone up in smoke - and perhaps your whole house too.

Buy a lottery ticket!

 

[ken_79-fj40]

I just spent about an hour in the garage pulling off more tape/split loom and inspecting the damage. I can certainly fix it, but it's going to be a lot of soldering and heat shrinking. Although probably a lot less than installing an after market harness. I'm going to simplify it as much as I can too. There's always been a lot of plugs under the hood that no longer went to anything, all that's going to go. So can the igniter, and some other stuff under there. I also discovered a third lead that looks like it was supposed to connect to the alternator that was tucked inside the split loom. Perhaps that's why the ammeter never worked. It also looks like the white/blue striped wire cooked right up to a factory splice on either end. It must have ground out on something. I think instead of a fusible link I'm going to just put in some heavy duty fuses. So I've certainly got my work cut out for me, but I should have it back on the road after a few full days. And yes i'm quite fortunate it didn't burn up the entire truck and my home. I'll bet there was a lot of smoke when it happened.

 

[joeyg1973]

I just spent about an hour in the garage pulling off more tape/split loom and inspecting the damage. I can certainly fix it, but it's going to be a lot of soldering and heat shrinking. Although probably a lot less than installing an after market harness. I'm going to simplify it as much as I can too. There's always been a lot of plugs under the hood that no longer went to anything, all that's going to go. So can the igniter, and some other stuff under there. I also discovered a third lead that looks like it was supposed to connect to the alternator that was tucked inside the split loom. Perhaps that's why the ammeter never worked. It also looks like the white/blue striped wire cooked right up to a factory splice on either end. It must have ground out on something. I think instead of a fusible link I'm going to just put in some heavy duty fuses. So I've certainly got my work cut out for me, but I should have it back on the road after a few full days. And yes i'm quite fortunate it didn't burn up the entire truck and my home. I'll bet there was a lot of smoke when it happened.

It's six of one half a dozen of the other at this point. I will always be an advocate for a new wiring harness. Makes no sense to me to put all that effort into fixing a hacked damaged 30 year old wiring harness. Always seems like you are trying to polish a turd to me.

 

[ken_79-fj40]

So I called cruiserparts.net this morning and they have a whole dash/underhood harness available in stock. It's actually a little more than the aftermarket EZ-Wire harness I was looking at initially, but it would also plug right in and I could have the truck running in a few hours instead of a few days trying to fix what i've got. And I still don't know where mine shorted out. They are also only a few hours away from me so I can go inspect it first. Looks like i'm taking a vacation day tomorrow.

 

[Plowboy]

If the burned out section is above the emergency brake handle, the lever at the end might be the problem.
When you pull out the handle, there is a small part of the levers that sort of overcenters. That makes a small slicing action at the top of the levers. That eventually cut into my harness and shorted out the lead(white/blue) and melted my harness the same way.

NEVER MIND , Just noticed "79"you prabably have the floor mounted emergency brake.

 

[antFJ]

holy $$$ its more than the EZ-wire?? i bet you can find one from a mudder for cheaper.. so youre in new england?? post in the yankee toys section to see if anyone has a harness they'd be willing to sell you..

 

[ken_79-fj40]

Yep, it's a little more money but a whole lot less work. And right now time is a very valuable thing. I'll bet there probably are a few people out there who might have a spare they would part with for less. But they likely don't offer any kind of warranty or take credit cards and i'm pretty cash poor from my engine rebuild and would like to enjoy the truck for a while before it gets cold again.

 

[Pin_Head]

Don't forget to get the fusible link too. That way your amp meter will work and you won't have this problem again if you don't find the short right away. If the wire between the ignition switch and fuse block burned, the short is at the fuse block. If the alternator wire is burned, it is the alternator that is shorted.

The only way an after market wire kit would be cheaper is if you value your time at less than $10 an hour.

Dont remove any unused wires; just tape them off on the harness. You never know when you might need them.

 

[ken_79-fj40]

The wiring is not shorted out between the fuse block and the ignition or in between the alternator and harness. I'm pretty sure it just grounded out on something, but I have no idea what. This last time it went up I wasn't around and the truck was sitting with the ignition off in the garage. I drove it wednesday night, changed my carb main jets thursday night, but never even turned the key or even got in the driver's seat, then got up friday to drive it and it had no power. My plan is to head out to Cruiserparts in the morning, and check out what they have. They say it's a complete underhood harness and the dash harness. If it looks good i'm going to head home, clean it up, and add a few leads for my tach, driving light switch illumination, radio, and electric choke. I think instead of cutting stuff off the harness I may just unwrap it and then loop it back in up under the dash. As it was before I had a jumper for my electric choke running off the driver's side harness, and nothing else on that side was hooked to anything.

 

[joeyg1973]

If you are going to unwrap it, you are going to want to get a bunch of goo off and lots of paper towels to clean all the old adhesive from the electrical tape off. Go out to one of the big box auto stores and get some plastic wire loom covering to replace the tape once you get it all cleaned up.

 

[Michael Hanson]

You can repair faster than replacing it all.Use marine high heat wire. Mike

 

[ken_79-fj40]

If you are going to unwrap it, you are going to want to get a bunch of goo off and lots of paper towels to clean all the old adhesive from the electrical tape off. Go out to one of the big box auto stores and get some plastic wire loom covering to replace the tape once you get it all cleaned up.

I've already got a big bag of zip ties, 3 rolls of shop towels, electrical parts cleaner, and lots of split loom in the garage. I'll probably pick up some dielectric grease tomorrow for the plugs too.

 

[joeyg1973]

I've already got a big bag of zip ties, 3 rolls of shop towels, electrical parts cleaner, and lots of split loom in the garage. I'll probably pick up some dielectric grease tomorrow for the plugs too.

You're a good man Charlie Brown.

 

[ken_79-fj40]

My truck is on the road to recovery. The harness Cruiserparts had was mint. I replaced the fusible links, cleaned it up, spliced in leads for my radio and tach and started installing it last night. Should be up and running after a few more hours tonight.

 

[Pin_Head]

You still need to find the short so the same thing doesn't happen. The short isn't necessarily where the wire is burned, but it can't be upstream of the short.