Wiring from scratch.

[jkgts1]

Okay, i've been stuck on this part of my project for a little while and have just been avoiding it. I am not an electrician so my knowledge is limited. So i have a 74 260z with a 2jzgte in it. I have a new engine harness that I had someone make for me. I purchased a pre made wiring harness with fuse block for the body. I kind of just need to know the basics which I really cannot seem to find.

1) I will run heavy gauge wire from the battery straight to the starter, correct?

2) also run a wire from the battery to a fuseable link or maxi fuse then to the aftermarket fuse block, correct? So, this will power my fuse block. Now the majority of other things, lights, fuel pump, gauges, etc will get power from the fuse block, correct?

3) I understand that relays are switchs and that they use low current to power larger current items. Example. When wiring up the fuel pump, im sticking a relay between the fuse block and fuel pump? So, I am powerig fuel pump with the relay and the power to the relay comes from the fuse block?

 

Sorry if all these seem simple, but I want to be sure I do it correctly. Last thing I want is for the car to catch on fire.

[Namor]

1. Yes you want heavy gauge wire between the battery and starter.  Generally these are something around 4 or 2 gauge.  Only downside to bigger is the additional weight.  

 

2. I would stick with what was done from the factory as far as # of fuses and ratings.  Unless you are upgrading something such as the fuel pump you mention in question 3.  Upgrade the fusible links to fuses and the fuse block to modern fuses, but keep them wired the same.  

 

3. Yes, basically if the original wiring isn't suitable to power your fuel pump then you run a new positive and negative to the fuel pump directly from the battery with a fuse and a relay in line.  Then you wire the original fuel pump wiring to the relay.  Original wires energize the relay, which will switch positions and energize the fuel pump.  

[Chris Duncan]

I would start with the wiring diagrams for the 260 and the car that the 2jzgte came from.

 

Also some "how to" books might help like HPBooks "Automotive Electrical Handbook"

 

Relays have two purposes, to allow smaller more compact switches on the dash and to shorten the heavy gauge wiring to "add lightness". Try to locate relays where they do keep the heavy gauge wire side of the circuit as short as possible. 

 

Also have a look at http://www.zspecialties.com/ on the left sidebar "tips and info" >> electrical. Basically you don't want to repeat the problems that exist with the early Z stock electrical.

 

Waytekwire is the cheapest source for bulk wire, connectors and wiring accessories for automotive.

 

One thing I've done on my Z's is to go to the next larger size wire on the headlights. I believe stock is 14 ga so bump it to 12 ga. (heavy side of the relay)

 

There are three ways to build wiring looms. Wrapping with electrical tape, covering with plastic flex tubing anchored with tape, and just using zip ties every 3 inches with no further insulation.

Edited October 24, 2013 by Chris Duncan

[jkgts1]

Thanks for the site, but I can't seem to select that part of the web page. I might need to look on my desk top at home. Yeah I really don't want to make mistakes with the wiring, even if Datsun made them, lol. I have bought 2 how to books, which are very informitive, but i'm the type that has to have everything laid out to see it. Hopefully it will come to me when I physically lay everything out.

[Chris Duncan]

I can access that site on either the desktop or Droid phone.

 

basically there's 4 problems with almost all 1st gen Z's.

 

1. the fuse box has some undersized wiring that melts

2. there are some inline fuses that are inadequate near the pass left knee.

3. the alternators are underpowered and have external regulator. You want something after '83 w/internal reg.

4. the headlights don't have a relay/s, all the power goes through the switches.

 

the biggest problem when sourcing parts is finding two-color wire. You can get a bunch of one-color but it's sometimes not enough and you end up having two wires of the same color next to each other. I solved this by painting the wires with a paint pen but it was a mediocre solution.

[jkgts1]

Okay thanks

I did buy an aftermarket fuse box with all the wiring hooed up, sorry might have forgot to mention the wire part on the first post. So, i hope the wiring that came with the kit is acceptable. I am not doing anything crazy, sound system huge amps and stuff, im bot even putting a radio in. I am using a 140 amp alternator that comes with that engine (internal regulator). Yeah I did read about the head light relays, so i will definitly run a couple of relays for those.