[Xsam1978]

So I’m a new member to this forum and I just got a 1978 280z not too long ago and the wiring is absolute trash, all diy, fuses everywhere, random wires not even attached to anything, you can imagine. I don’t even know if everything is working properly because I can’t figure it out. I wanted to re-do it all myself and buy a wiring harness online. Only thing is I also wanted to shave the engine bay the most as possible so I wasn’t sure on buying a universal kit. I saw a few people on here got the ez wiring kit as it’s cheap and easy but again wasn’t sure as I saw it’s a universal kit. Would there be either a 280z kit or a universal kit that fits well for relatively cheap? (Under ~$400 preferably)
Thanks

 

[pilgrim]

Perhaps someone has a kit, or knows a vendor that has one. Personally, I'd work with the factory service manual and restore the wiring harness to stock. Usually that is possible, and less work than running a new harness.

 

[steve240Z73]

No, there is no 280Z kit. If you get a generic wiring harness then you'll need to adapt the wire lengths, and forget about finding some of the Yazaki connectors. The AMP connectors are available if you know what you're looking for.

@zmanofwashington may still have the wiring harnesses for a 78. It would be worth asking him.

Unfortunately too many previous owners of S30s "fix" wiring issues with little to no clue about what they are doing.

 

[pilgrim]

Ain't it true. With almost any used car, I figure the first thing to do is remove any electronic gear installed by the previous owner and return the wiring harness to stock so you know what you are dealing with. The butchery can be impressive.

 

[steve240Z73]

Ain't it true. With almost any used car, I figure the first thing to do is remove any electronic gear installed by the previous owner and return the wiring harness to stock so you know what you are dealing with. The butchery can be impressive.

Yes, a friend picked up a 77 that I worked on some a couple of weeks back. Someone jury-rigged the wiring in such a way that he cross connected something in the dash with black/white wire. The wire he cross connected usually gets its power from the ignition relay, so when you turn the key off, the relay stays powered up. I narrowed it down to something off the gauge fuse, but I didn't have the chance to dig deeper. Since he doesn't need the fuse plugged in, he has run the car with that fuse out.

 

[kickstand80]

Free Factory Service Manual here:
S30 FSM

The engine bay EFI wire harness is basically a stand alone and only goes from the ECU to the engine with a connection to the battery via the EFI relays. Study the wire diagram in the FSM and understand what and where before you dive into this undertaking. The better you understand how the EFI system work the better off you will be to tackle any and all of the "projects" that you have taken on in purchasing a Z.
One thing to remember is that red is not always a power wire and black in not always a ground wire in the Z world.
Welcome to the world of ZZZZZZZZZ!

 

[Xsam1978]

Thank you to everyone I’ll look into the manuals and see if I can restore back to stock

 

[steve240Z73]

Here's a link to wiring diagrams: Wiring Diagrams
The FSM has some nice breakouts of a lot of the different systems in the BE section, too.

 

[OldSchoolZGuy]

The wiring diagrams are a nightmare, especially when it comes to the switches. None of the '72 diagrams I have come across online or in the actual original '72 FSM hardcopy I have match my car completely. Vintage Connections - Motorcycle Terminals and Connectors - Vintage Connections can provide a complete connector/pin rebuild kit with the original style connectors which is what I am using to rebuild my harnesses from scratch. Unfortunately I have completely redesigned much of the wiring for my restoration integrating relays into most load circuits and expanding and isolating my fusing circuits using separate BlueSea Systems fuse boxes for the battery, accessory and ignition circuits with the last two on 130 amp relays controlled by the ignition switch positions. All of this was done to preserve the switch contacts in the OEM turn signal, wiper motor and headlight switches by using those switches to drive relays that will carry the load currents rather than through the switch contacts. After the amount of money I had to spend on obtaining NOS replacement switch assemblies, I want them to last as long as possible which I will help them do by vastly reducing the current they have to deal with on a day to day basis. I know for a fact that Norm at ZeddSaver has some of the factory harness assemblies in stock. I've talked to him about sending me some of them so I can duplicate them for him to use up some of the remaining wire I will have after building my custom harnesses. But be prepared to spend some cash as they will not be cheap.

 

[steve240Z73]

As someone who has to work with a variety of wiring diagrams, I have to disagree. The wiring diagrams aren't that difficult to read, nor are the switch layouts.
While Vintage Connections has some of the connectors for a 77, they don't have many that are needed if you're doing a complete re-wire.

I do agree that there are wiring diagram discrepancies. I have been helping someone with rebuilding a 73 wiring harness. It's not surprising since those drawings were probably maintained on vellum in that timeframe, and it is a challenge to keep up with all of the design changes. I know the latter issue first hand trying to update as-built drawings when the field engineers don't provide complete documentation.

I also agree that it won't be cheap, but few worthwhile things are.

 

[OldSchoolZGuy]

When you have multiple versions of the same schematic for the same year and the wire colors and the switch diagrams have differences on each one, that is an unnecessary pain in the backside. I've spent my entire 50 year career in the aerospace industry dealing with schematics and circuitry and I've even managed to figure out the German schematics on my 911 which were bad enough but these for my '72 Z truly suck, big time. It is why I'm completely redrawing them to match my wiring redesign but in a way that more closely resembles what Nissan did a few years later, isolating individual circuits and only showing the wires and affected connector pins for that circuit. It's not a matter of maybe someone mucking up the wiring before we got it as my Father was the original owner. This confused state is how it came from the Nissan factory.