The "Official" FJ25 Wiring Harness Thread

[mmcinnis]

Rear chassis wiring can be anything you want. Pure OEM, use later model dual element lights, or even the three way modern lights with separate reverse, turn, and brake/park. That last one would require a bit of tinkering with the turn signal wiring. I can even add Hazard lights using a later 69-72 switch if you need them.

However before I start building custom harnesses, I need to finish documenting the OEM harnesses!

The real question is will most folks want OEM harnesses? The reason for that question needing to be answered now? I am looking at what wire would have to be ordered in and it would be several hundred dollars of those four colors in several different gauges. Colors and gauges I can not use anywhere else. If I replaced the four colors used in the FJ25 with the later Toyota wire colors and gauges I would not have to order anything new...

I agree with jim, i think it looking oem but with a modern twist/safety factor. Happy New Year to all. Thanks a million coolerman. great job.

 

[Coolerman]

Yesterday I had hopefully, my last eye surgery! PKRE procedure to repair the vision the previous detached retina surgery messed with. Today I am recovering so I plan to work a bit on the FJ25 harness documentation. Need to get the build sheet started. I will post some more pics later today.

 

[mmcinnis]

Yesterday I had hopefully, my last eye surgery! PKRE procedure to repair the vision the previous detached retina surgery messed with. Today I am recovering so I plan to work a bit on the FJ25 harness documentation. Need to get the build sheet started. I will post some more pics later today.

Wish you a speedy recovery, take your time. Dont rush for me! great job Mike

 

[Coolerman]

Well I didn't get any pics this weekend as the eye thing just drove me nuts! So here are a couple of progress pics.

First is a pic of the fuse panel separated from the harness. It is in excellent condition if you ignore all the beige paint.

After a soak in some white vinegar and a tooth brush scrubbing we have this:

When I do my next batch of Soda Blasting I should be able to get the paint off. At that time I will also soda blast the switches to clean them up. I just wanted to clean this fuse panel up enough to ensure when I'm metering out wires that I am not measuring corrosion. I put all new fuses in also.

 

[Coolerman]

Don't forget the yellow and white streamer outside the wrap, always look for that in an original.

I just re-read this. I don't recall seeing any "streamers"? Exactly what are they, and where would they be located?

I am used to seeing the Toyota ID label with the harness part number on it...

 

[mmcinnis]

Well I didn't get any pics this weekend as the eye thing just drove me nuts! So here are a couple of progress pics.

First is a pic of the fuse panel separated from the harness. It is in excellent condition if you ignore all the beige paint.View attachment 1379632

After a soak in some white vinegar and a tooth brush scrubbing we have this:

View attachment 1379636

When I do my next batch of Soda Blasting I should be able to get the paint off. At that time I will also soda blast the switches to clean them up. I just wanted to clean this fuse panel up enough to ensure when I'm metering out wires that I am not measuring corrosion. I put all new fuses in also.

Wow, looks great!

 

[hdjtachtig]

to ensure when I'm metering out wires that I am not measuring corrosion. I put all new fuses in also.

Point of attention: We had some issues with bad connection between the fuse holders and the terminals.

 

[Cruiser_Nerd]

I just re-read this. I don't recall seeing any "streamers"? Exactly what are they, and where would they be located?

I am used to seeing the Toyota ID label with the harness part number on it...

Bad description on my part. Yellow tape on ends, white vinyl strip with ends tucked into the wrap (at the fender clip). Found at both fender lighting terminal strips and rear harness at firewall connection. White vinyl could very well of had a part number on it since it would be three separate pieces, no sign of a number on mine.

 

[Coolerman]

Yes, that is where the part number for that harness would have been printed. Toyota must have switched to a better ink later on as most of the early FJ40 harnesses I have worked with can still be read!

 

[Coolerman]

Point of attention: We had some issues with bad connection between the fuse holders and the terminals.

Corrosion or loose rivets? That is why everyone should pull their fuse panel and soak it in white vinegar for an hour. It will remove any rust and corrosion between the parts. A quick hit with a wire wheel on Dremel tool and it will look new! The rivets can be tightened thought that would require a bit more disassembly. I will check this one to see if any are loose. Thanks for that tip.

 

[Living in the Past]

Corrosion or loose rivets? That is why everyone should pull their fuse panel and soak it in white vinegar for an hour. It will remove any rust and corrosion between the parts. A quick hit with a wire wheel on Dremel tool and it will look new! The rivets can be tightened thought that would require a bit more disassembly. I will check this one to see if any are loose. Thanks for that tip.

I've tried to solder the rivets with no luck. I have been able to braze many dissimilar metals with silver solder but the that much heat would destroy the insulating material. After a good cleaning have had good luck using a punch and anvil to seat the rivets.

 

[Coolerman]

Update!
Last night I completed the first ever FJ25 Harness Build sheet! This build sheet can be used to build new FJ25 harnesses.
What is a build sheet you ask? Well the first time I saw the early to 1969 FJ40 wiring documentation, I noticed there was a sheet that listed all the wires, their sizes, base color/stripe, function, and most importantly, where the wires started and ended! It also shows where splices were located in the harness. It took me a while to figure out the "addressing scheme" that Toyota used, but once I did, I used it for all my harness builds.

Using the colored schematic I was provided, a 67 build sheet and my multi-meter, I began tracing out each wire.
I used the 67 build sheet as a comparison just to see how many wires are shared between the two years. (A few)

I quickly discovered a very interesting thing: There are NO splices in an FJ25 harness! None! All wires are point to point. Instead of splicing Toyota just ran two wires to a common connection point like a fuse block terminal or the key switch. This wastes wire, but makes trouble shooting a whole lot easier!

After I traced every wire, I used a set of calipers to measure the wire diameters to figure out the wire gauges. This revealed another surprise. Everyone knows that Toyota used metric wire gauges that do not line up exactly with the American Standard Wire Gauge. Measuring the outside diameter of the wire, revealed this: The statement I made above about Toyota using larger than normal wires sizes is actually incorrect! Compared to later harnesses, this 1960 harness is right in line with them. 10 ga for the main power circuit, 12ga for headlight switch, and key switch BAT, 14 ga for head lights from dimmer, 16 gauge for turn/brake wires, and 18 ga for meter sensors. The wires simply LOOK bigger than they actually are!

This is good news for me as I will not have to order $1000's of dollars worth of wire to duplicate these harnesses! I only have to order in 4 "new" sizes in order to build a pure OEM harness with solid colored wires and colored heat shrink. If I build them using striped wire instead of colored heat shrink to identify them, I only need order in 3 new sizes.

So without further ado, here is the Build sheet!

 

[Coolerman]

Some Quick questions:

Are these double female bullet connectors connected to the turn signal wiring OEM?

How were the OEM turn dash light indicators connected to the turn signal wires? On this harness they are spliced in. On later harnesses there were triple female bullet connectors that they plugged into.

Since the OEM FJ25 turn signal switch seems to be unavailable, can the later early turn switch be used or will it not mount to the column correctly?

 

[pardion]

Early turn signal levers have the rod that goes down the column to the switch. FJ 25's do not have the cut in the dash for the rod to pass thru.

 

[Coolerman]

Thanks John, I figured there had to be a reason no one was using them in the FJ25's. Any idea about those inline splice connectors mentioned above? Or how the turn signal dash indicators lights were mated to the turn signal wiring?

 

[tahoe40/45]

Thanks John, I figured there had to be a reason no one was using them in the FJ25's. Any idea about those inline splice connectors mentioned above? Or how the turn signal dash indicators lights were mated to the turn signal wiring?

I was actually in the process of making a turn signal switch for my FJ25 out of a FJ40 switch (then i found a correct switch). I was going to mount the switch up high (where the 25 switch mounts) and run the wires down the steering column tube, connect a lever to where the rod connects, then fake some kind of housing. I hope that makes since.
On my harness i have similar bullet connectors just like a 40, so my dash lights just plug inline with with the green/orange and green/yellow wires.

First photo is of TLC 4x4's old FJ25, now in museum in Utah. Second is of my harness. Hope this helps.

 

[Coolerman]

Yes! I had a suspicion those inline things weren't stock, but that proves it. Now I can effect the correct repairs on this harness Thank you so much!

 

[mmcinnis]

Started messing with the motor today.

Ran into a few wires from the generator.

 

[Coolerman]

I need to document one of those early generator sub-harnesses. I have some specs on an early FJ40 generator sub-harness and wonder if they are the same?
Early FJ40 Generator Sub-Harness specs:
Length about 67"
WB 16ga
WG 16ga
WR 10 ga

For this FJ25 sub-harness I would need to know: Wire length, wire gauge, wire base color, wire terminal heat shrink color, terminal type/size.

I assume that sub-harness is from the harness I have?

 

[mmcinnis]

I need to document one of those early generator sub-harnesses. I have some specs on an early FJ40 generator sub-harness and wonder if they are the same?
Early FJ40 Generator Sub-Harness specs:
Length about 67"
WB 16ga
WG 16ga
WR 10 ga

For this FJ25 sub-harness I would need to know: Wire length, wire gauge, wire base color, wire terminal heat shrink color, terminal type/size.

I assume that sub-harness is from the harness I have?

I could send it to ya?