REWIRE (1 Viewer)

[Joe45]

Howdy.

I would like to rewire my HJ45. I've seen some places that sell sort of universal wiring setups. Does the wiring have to be diesel specific?
Someone mentioned in another thread that if I rewire using an aftermarket harness, the factory sche,atics will no longer work. I don't think I mind that in an exchange for modern, new wires that aren't all rigged up and patched up, etc. Plus I can just have a new wiring schematic for my truck printed and keep it with the log book.

Still, suggestions are welcome.

 

[V8FJ4078]

Can you replace just the wires that are rigged up and patched up?
I rebuilt a new harness, copying my old harness and it took time, but I wasn't trying to retro fit a aftermarket harness into something and sorting out the switching issues. I did this in my 78 FJ40.

 

[charliemeyer007]

How much wiring is there? My 72 FJ40 is basic. If I was to redo it I would skip all color code stuff like black with a white stripe and use one of those label printers for wires

 

[ryanwk628]

I rebuilt my old harness, but it is all pretty simple if you wanted to make it from scratch. Learned a lot. Use the stock diagram for a reference. The tricky part for me was everything associated with the turn signals but I got it sorted. Later models had more circuits, but I think they used less bullet connectors. At work we use wire labels, Id take that over colored wire, especially when the colors are used more than once or are so close. I numbered few for my own reference



@WiringRescure on youtube also has some great instructional for automotive circuits and how they work

 

[Joe45]

Can you replace just the wires that are rigged up and patched up?
I rebuilt a new harness, copying my old harness and it took time, but I wasn't trying to retro fit a aftermarket harness into something and sorting out the switching issues. I did this in my 78 FJ40.

How much wiring is there? My 72 FJ40 is basic. If I was to redo it I would skip all color code stuff like black with a white stripe and use one of those label printers for wires

Someone had suggested that also in another thread, and yeah, it's a possibility. I could, for example, start with the break lights and work my way back to the fuse box, etc.
I'd like to replace the fuse box and those glass fuses. Have looked at marine breaker boxes instead of fuses-not sure if it's worth it though. Could also just go for the newer plastic ones.

The idea of labeling the wires is spot on. I figure put a label at every junction and halfway at least. The only color variation I would use, maybe, is lets say red/black for all the standard wiring, and something like green/black w/white for accessories.

But I am looking at what y'all say since you've done it already.

THANK YOU!

 

[Joe45]

I rebuilt my old harness, but it is all pretty simple if you wanted to make it from scratch. Learned a lot. Use the stock diagram for a reference. The tricky part for me was everything associated with the turn signals but I got it sorted. Later models had more circuits, but I think they used less bullet connectors. At work we use wire labels, Id take that over colored wire, especially when the colors are used more than once or are so close. I numbered few for my own reference



@WiringRescure on youtube also has some great instructional for automotive circuits and how they work

Damn! That video is awesome!
THANK YOU!

 

[pb4ugo]

Someone had suggested that also in another thread, and yeah, it's a possibility. I could, for example, start with the break lights and work my way back to the fuse box, etc.
I'd like to replace the fuse box and those glass fuses. Have looked at marine breaker boxes instead of fuses-not sure if it's worth it though. Could also just go for the newer plastic ones.

The idea of labeling the wires is spot on. I figure put a label at every junction and halfway at least. The only color variation I would use, maybe, is lets say red/black for all the standard wiring, and something like green/black w/white for accessories.

But I am looking at what y'all say since you've done it already.

THANK YOU!

IMO, each circuit needs its own color coded wire. I would rebuild or remake a wiring harness or get an aftermarket kit, so you can easily ID each circuit. Painless wiring is not painless, you still have to adapt the stk plugs to it. Your going to hate life when all the wiring is only a couple of colors and a problem arises and all the labels fall off or the writing fades. When most of the colors are the same your going to be tracing one red wire amongst a bunch of red wires. Coolerman sells color correct wire, plugs and terminals. Personally I'd pull your existing harness and lay it out on a sheet of plywood, remove all the hack and see what is left. A lot of times you can repair what you have while using parts and wires from coolerman. That's what I did on my trail 40. I had a number of old hacked wiring harnesses I could cut wire out of to make repairs. On my 2nd 40 most all my wiring was fine with minimal hacks in it, so its repair was done while in the vehicle. Even the electrical connections to the SBC are stk FJ40 colors. I only added 2 wires that weren't factory, one to an ALT idiot light and 1 from the GM ALT big post to the batt.

 

[Joe45]

IMO, each circuit needs its own color coded wire. I would rebuild or remake a wiring harness or get an aftermarket kit, so you can easily ID each circuit. Painless wiring is not painless, you still have to adapt the stk plugs to it. Your going to hate life when all the wiring is only a couple of colors and a problem arises and all the labels fall off or the writing fades. When most of the colors are the same your going to be tracing one red wire amongst a bunch of red wires. Coolerman sells color correct wire, plugs and terminals. Personally I'd pull your existing harness and lay it out on a sheet of plywood, remove all the hack and see what is left. A lot of times you can repair what you have while using parts and wires from coolerman. That's what I did on my trail 40. I had a number of old hacked wiring harnesses I could cut wire out of to make repairs. On my 2nd 40 most all my wiring was fine with minimal hacks in it, so its repair was done while in the vehicle. Even the electrical connections to the SBC are stk FJ40 colors. I only added 2 wires that weren't factory, one to an ALT idiot light and 1 from the GM ALT big post to the batt.

I'll consider that as well, thanks.
Actually, in a vehicle this simple, it wouldn't take that many colors anyway.
I'll have to think on all this.

Right now I am just gathering information, as I don't have a place to work other than in the yard, and I'm not dealing with that nightmare.

• I live at just under 7,000 feet.
• Monsoon is about to start.
• By October we sometimes get snow and, at the least, it starts to get cold.
• By December we're getting into freezing temperatures or just above, and often below.

Obviously a resto-mod under these conditions is not possible.

I may build myself a simple garage: either a cheap carport and enclose it, or more likely lean-to once my shop is up, hopefully by September. This way I can at least be out of the weather and have some heat.

Thanks for the info, as it is very valuable!

 

[45Dougal]

How about some photos of the worst parts of the hacked wiring to give a sense of how bad it is?

I started with a lot of hack, but a few days of effort made a big difference.

Work your way through it one circuit at a time.
Pull all the fuses, bar one, and check what works and doesn't work.

Draw a schematic correct to your truck, and then figure what you want to change.

That rear harness from the bulkhead backwards along the chassis is a very simple place to start, and is easy enough to replace entirely.
Basically lights, fuel sender, and reverse switch + maybe 4wd switch?

 

[Joe45]

How about some photos of the worst parts of the hacked wiring to give a sense of how bad it is?

I started with a lot of hack, but a few days of effort made a big difference.

Work your way through it one circuit at a time.
Pull all the fuses, bar one, and check what works and doesn't work.

Draw a scenario correct to your truck, and then figure what you want to change.

That rear harness from the bulkhead backwards along the chassis is a very simple place to start, and is easy enough to replace entirely.
Basically lights, fuel sender, and reverse switch + maybe 4wd switch?

That's a good idea.
I'll take pictures and post them as soon as I can-when I start.
Thank you!

 

[peesalot]

I re wired my 40, got 2 aftermarket fuse blocks, 1 for always hot, & 1 for Ign. on hot. ran a separate circuit for almost everything ( 21 in total ) . 1 thing at a time , run wires, rerun so they look good, make harness wraps & secure points, it isnt that hard. The blinker/brake/hazard circuit is the hardest one to figure.

 

[pb4ugo]

You can probably pull the main wiring harness in less than an hour and it maybe take slightly longer on the install. The main harness typically consist under the dash and the engine compartment forward on both sides. You can work or rebuild the harness at a different location. Fyi.

 

[ryanwk628]

The blinker/brake/hazard circuit is the hardest one to figure.

These helped me understand the wiring of blinkers and single multi use tail lights and running lights and are how I would do it if starting from scratch instead of repairing the Toyota stuff

 

[Joe45]

These helped me understand the wiring of blinkers and single multi use tail lights and running lights and are how I would do it if starting from scratch instead of repairing the Toyota stuff

VERY useful videos! Thank you!
I would likely use different bulbs for the brakes and flashers, as that's how my HJ is set up, like in the first video.

 

[Joe45]

Was going to make notes of my wires: colors, etc., but it's a mess. The wires to the front turn signals are taped up and I can't tell the colors on the left, or if they were chopped and spliced. Don't want to open up that can of worms until I have a place to work and use of another vehicle. Right now my wife is using the FJC until she gets another car. Also have to build a garage: at least a simple lean-to style against my workshop. Even if its just enough to work out of the freezing cold, snow, and rain.

So here's my plan once I do get a place to work in. Please let me know if I am missing anything or have a wrong idea.

1. Label all wire ends/terminals regarding function (test before removal).
2. Remove wires and fuse box from vehicle, labeling all points of contact if any disconnecting/cutting is necessary.
3. Lay out the removed entire harness on a large work area.
4. Measure and note each wire's length, color, and gauge.
5. Note fuse box fuse amps and use.
6. Order new wires, terminals, fuse boxes, etc. using modern, better materials.
7. Order seperate fuse box etc. for accessories such as fridge, AC, lights, winch...
8. Assemble new harness.
9. Test flow of electricity using a battery and simple electric tester.
10. Draw out the wiring diagram noting purpose, color, gauge, etc.
11. Install in vehicle.
12. Test on vehicle.
13. Put on my kilt and run around the truck with a lit torch in one hand and either a sword or axe in the other, screaming.
14. If I have advanced beyond the practice chanter by then, play a tune on the bagpipes.
15. Drive.

I will save the original loom just in case someone offers me $5,000,000 to buy the truck but only if I still have all the original wires.

 

[V8FJ4078]

I laid mine out like this then followed and documented each wire and slowly build the duplicate harness. - lots of time, but WORTH IT!
Old one is underneath the new one I am building, I plugged in the switches as I finished each wire combination for the switch.
You will find splices in the harness as well, I started at the fuse block and worked out from that.

Test fit in truck before wrapping the harness.

 

[Joe45]

I laid mine out like this then followed and documented each wire and slowly build the duplicate harness. - lots of time, but WORTH IT!
Old one is underneath the new one I am building, I plugged in the switches as I finished each wire combination for the switch.
You will find splices in the harness as well, I started at the fuse block and worked out from that.

View attachment 3400560View attachment 3400561View attachment 3400563
Test fit in truck before wrapping the harness.

View attachment 3400565View attachment 3400566View attachment 3400567

That's looks great!
Back around 1990 I rewired my Jeep CJ7 with a Painless Wiring kit. Took two days taking my time. I made maybe three phone calls and they cleared things up (a couple of extra wires I didn't know what to do with).

I remember the fuse box, wired up, popped right on and I screwed the other side in, then just took the wires to the appropriate connections, and that was it.

But must admit I'm a little intimidated. Propably I'm overthinking since I'm new to diesel.

 

[Truck Enthusiast2]

Howdy.

I would like to rewire my HJ45. I've seen some places that sell sort of universal wiring setups. Does the wiring have to be diesel specific?
Someone mentioned in another thread that if I rewire using an aftermarket harness, the factory sche,atics will no longer work. I don't think I mind that in an exchange for modern, new wires that aren't all rigged up and patched up, etc. Plus I can just have a new wiring schematic for my truck printed and keep it with the log book.

Still, suggestions are welcome.

While universal wiring setups can be handy, diesel-specific wiring might optimize performance. Using an aftermarket harness can modernize your wiring, but adapting factory schematics might be tricky. Taking it step by step and focusing on clean runs and secure points will yield good results.

 

[Joe45]

While universal wiring setups can be handy, diesel-specific wiring might optimize performance. Using an aftermarket harness can modernize your wiring, but adapting factory schematics might be tricky. Taking it step by step and focusing on clean runs and secure points will yield good results.

Yeah I've decided to build the new loom myself following the original. Makes sense that doing it this way will give an outcome closest to the original.