Electrical Wiring Loom Build (1 Viewer)

[AYM707]

Thanks @nabbasi

As a Mech Eng, I always think of flow going in 1 direction, but I forget, that in the electrical world, power "flow" can be multi-directional depending on which switches / devices are engaged / energized.

I just ignored the ammeter wire circuit as I thought it was only for battery charging, but that is actually feeding the Ignition Switch, when the Alternator is not engaged.

 

[nabbasi]

Thanks @nabbasi

As a Mech Eng, I always think of flow going in 1 direction, but I forget, that in the electrical world, power "flow" can be multi-directional depending on which switches / devices are engaged / energized.

I just ignored the ammeter wire circuit as I thought it was only for battery charging, but that is actually feeding the Ignition Switch, when the Alternator is not engaged.

I do, too! I think I even suggested earlier making sure you note the direction the current is going, but failed to mention “except for the charging system.” I’m sorry about that..it might have saved you some confusion.

I just had an incident where I had a dead battery in my ‘78. I need to figure out if the battery was just too drained for the charging system to properly re-charge since it’s supposed to only “maintain” or “top off” and not really charge a heavily depleted battery.

Not sure if this is coincidental or not, but I also went with some very, very stout battery cables from @Fourrunner in my ‘67. After using those cables and cleaning up grounds, I don’t have weird grounding issues that I’m experiencing in my ‘67. Just something to keep in mind when you get to harness installation/ testing.

 

[ToyotaMatt]

Now that the Beast is gone, I can concentrate on other projects. My FJ40's electrical wiring is an absolute mess and it drives me crazy. Grounding issues, wires sliced / diced, dead wires just hanging around. I am also considering adding an electrical heater & USB ports; so I need some extra power. I know I can buy a harness, but what's the fun in that!!!

I've read several threads and watch several youtube videos on how to do it. So I've chalked up a plan, so I dont screw it up.

1. Schematic Review
   • Detailed review of the electrical schematic.
   • Identify all switches / devices on the schematic and match them with switches / devices on my FJ40.
   • All wiring to be labelled.
   • Do an electrical calculation to confirm the load / current (fuse rating).
2. Create Test Bed
   • I want to create a test bed, where I will test each circuit to ensure the wiring is correct.
   • Test bed to mirror the schematic, using small bulbs to represent devices.
   • Generic switches to be used. Some actual FJ40 switches may be used.
3. Remove Existing Wiring Loom
   • Carefully remove the existing wiring loom.
   • Each wire to be labelled; showing where it was connected.
4. Install New Wiring Loom
   • Install the new loom.
   • Fingers crossed - hoping I did not screw it up!!

The intent is to post all my work online, so that others may review my work and highlight any issues / mistakes. Also, if anyone wants to build their own loom, they could use my work as a starting point.

This is going to a long / slow project, with Phases 3-4 being in the winter.

.

which 40 are we working with here ?

-
1983 FJ45LP-K (QAT)

or

1982 FJ40LV-KC (KSA)


this matters with most of your post #1 # points ...

 

[AYM707]

.

which 40 are we working with here ?

-
1983 FJ45LP-K (QAT)

or

1982 FJ40LV-KC (KSA)


this matters with most of your post #1 # points ...

I'm working on the 1982 FJ40LV-KC (KSA).

 

[stewt]

Hey AYM, I'm doing a very similar project, mapping and making a 86' fj45 harness because mine short circuited and melted. What software are you using to map your harness if any?

 

[AYM707]

Hey AYM, I'm doing a very similar project, mapping and making a 86' fj45 harness because mine short circuited and melted. What software are you using to map your harness if any?

great!!

Software???? I'm just using auto-cad to draw my schematic. The rest is on excel.

What about you? what software?

 

[stewt]

great!!

Software???? I'm just using auto-cad to draw my schematic. The rest is on excel.

What about you? what software?

I used canva, its a more simple cad software for ipad, computer etc. It took me a few weeks to finish it but it looks pretty beautiful. Ill attach a photo of it below. Also, the trucks a Venezuelan built CKD, so theres not as many electrical components found in regular late fj40/5s.

 

[AYM707]

I used canva, its a more simple cad software for ipad, computer etc. It took me a few weeks to finish it but it looks pretty beautiful. Ill attach a photo of it below. Also, the trucks a Venezuelan built CKD, so theres not as many electrical components found in regular late fj40/5s.

View attachment 3905343

WOW!!! That's impressive. The more I look at it the more intrigued. I see you went with an actual approach. Did you pull out your existing harness and then map everything? I like the way its set-up; it shows where everything is located complete with the connector details. Do you have the wire lengths of each segment?

I've taken a slightly different route. I'm actually trying to reproduce the Toyota schematic, based on a GCC / Saudi vehicle. During the winter, I plan to map my existing wiring and then compare it with my schematic. I also plan to make a test board before I pull my existing harness out. Its going to be a long project.

 

[stewt]

WOW!!! That's impressive. The more I look at it the more intrigued. I see you went with an actual approach. Did you pull out your existing harness and then map everything? I like the way its set-up; it shows where everything is located complete with the connector details. Do you have the wire lengths of each segment?

I've taken a slightly different route. I'm actually trying to reproduce the Toyota schematic, based on a GCC / Saudi vehicle. During the winter, I plan to map my existing wiring and then compare it with my schematic. I also plan to make a test board before I pull my existing harness out. Its going to be a long project.

I pulled all of it, labeled what i knew was what and where and for the stuff I had no idea about, I tracked the wires from connector to connector. Basically a big ol puzzle. I did not measure each wire cause it was all melted, but I know my general measurements. I'm figuring it out as I go. All of this is pretty new to me but I'm confident I can do it.

 

[cruisermatt]

 

[Engineer8000]

@cruisermatt, what do you use for harness wrap at your shop?

 

[cruisermatt]

@cruisermatt, what do you use for harness wrap at your shop?

HD Tesa tape!