ground-up rewire

[Jesse OBrien]

As some of you may already know, my wiring in my 240z is a complete mess. Nothing is bundled together correctly, opposite ends of the same wire aren't labeled the same more often than not, no fuse box existed when I got the car, and some of the wiring is just flat out missing. I've been planning a complete rewire of the car, and researched:

• modifying the wiring I have now, correcting problems as I come across them
  
• painless wiring kits
  
• complete rewire from the ground up

I've decided upon a complete rewire for a number of reasons:

1. I can clean up the appearance of the wiring greatly, tucking and bundling wires as I need to
   
2. I end up with a detailed wiring diagram that I'm 100% certain is accurate
   
3. I can use aviation circuit breakers in place of fuses

I just drew up a basic wiring diagram that I plan to use for the installation and purchase of wires (I'll have to get circuit breakers depending upon the amperage needs of each individual component, which I haven't researched yet.

 

I also need a new front fairing/cowling/valance, so I'll be wiring up my jdm corner lights that came with the car, and fabricating a brake light setup. I'll post the wiring diagram as soon as it's complete (and I can get a picture of it). It's very basic, since my sbc is so simplistic (starter motor, alternator, single-wire distributor, and electric choke is all it needs).

 

Does anybody have any recommendations for a reputable aircraft parts dealer (or anywhere I can get good switched circuit breakers) and what relays are actually necessary for the 240z?

[supertip]

You should post a picture of the diagram you made, this is something I would like to do as well.

[essdeezee]

Good start of a plan, as I see it. However, in previous threads I had seen concern from some of the experienced members about using circuit breakers in place of fuses.

 

If they are popping regularly, something is wrong with your components or wiring design. I'm about to embark on some rewiring of my own, and according to my research, fuses are in order.

 

I'm planning (at this point) on spending some time perusing the junkyards for a suitable fuse/power distribution/relay block for the main harness. Last trip, I saw a nice setup in a mid nineties Mercury station wagon. Plenty of circuits, and spots for 5-6 relays (IIRC, Pics in a week or two), and a nifty clean looking OEM plastic cover for the whole shebang.

 

In addition, I'll be running my driving lights and electric fan from a separate maxi-fuse distribution block off the alternator feed (CS 144, thanks KTM!). The fuse block is available at your local Wal-Mart for 10 bucks and comes with 2x40A maxi fuses. Nearby, you should be able to find a kit with 50 and 100A fuses for like 4-5 bucks (Check the car stereo area for this stuff).

 

I feel strongly that a properly engineered setup should rarely blow fuses, and thus breakers are at best a waste of money, but more likely, a potential fire hazard.

 

That being said, good luck and keep us posted!

[Jesse OBrien]

Good start of a plan, as I see it. However, in previous threads I had seen concern from some of the experienced members about using circuit breakers in place of fuses.

 

If they are popping regularly, something is wrong with your components or wiring design. I'm about to embark on some rewiring of my own, and according to my research, fuses are in order.

 

If your wiring is set up properly, there isn't a difference between fuses and circuit breakers. I'm looking at circuit breakers as a more reasonable solution for future diagnostic purposes only. Costs won't be vastly different, and as long as the driver (me) is intelligent to NOT immediately and repeatedly flip the circuit breakers if they blow, there should be no more fire hazard than with fuses (correct me if I'm wrong, electrical engineers).

 

I'm planning (at this point) on spending some time perusing the junkyards for a suitable fuse/power distribution/relay block for the main harness. Last trip, I saw a nice setup in a mid nineties Mercury station wagon. Plenty of circuits, and spots for 5-6 relays (IIRC, Pics in a week or two), and a nifty clean looking OEM plastic cover for the whole shebang.

 

In addition, I'll be running my driving lights and electric fan from a separate maxi-fuse distribution block off the alternator feed (CS 144, thanks KTM!). The fuse block is available at your local Wal-Mart for 10 bucks and comes with 2x40A maxi fuses. Nearby, you should be able to find a kit with 50 and 100A fuses for like 4-5 bucks (Check the car stereo area for this stuff).

 

While I like the stock look, I don't like the excess. Trying to figure out what's in use and what's dormant from a different fusebox is just unnecessary. I like my electrical to be brought down to the bare minimum.

 

I feel strongly that a properly engineered setup should rarely blow fuses, and thus breakers are at best a waste of money, but more likely, a potential fire hazard.

 

That being said, good luck and keep us posted!

 

I agree, but I hate having fuses rattling around in the glove box "just in case". Circuit breakers are easy and quick to flip, almost like having a can of fix-a-flat instead of a spare tire (fix-a-flat is lighter and more minimalistic, and for all intensive purposes serves the same need as a spare tire).

 

Having said that, here's my running list of circuits, organized by switches:

• electrical components (all on their own separate circuit)
  • horn button
    
  • windshield wipers switch + relay (for speeds and intermittent, donor wiper motors to be decided)
    
  • choke (electric edlebrock choke)
    
  • *possibly* alarm system (I'm not convinced that alarms actually accomplish anything. I'm considering adding a pda with a camera and wireless, and any time someone sits in the driver's seat it takes a picture and attempts to email all pictures to me whenever wireless internet is present. That would give me a picture of anyone who stole or attempted to steal my car, as well as a last known location. Then I can break out the baseball bat and go meet up with them.)
    
  • ignition
    • keypad - numbered keypad which, upon successful entry of the ignition code, provides power to the following:
      • distributor
        
      • starter motor button(pushbutton switch)
        
      • alternator
        
      • cooling fans
        
      • gauges
        • tach
          
        • speedometer
          
        • oil pressure
          
        • coolant temperature
          
        • fuel level

    • lights - separate circuit from the main 'running' circuit. (I'm going to have to research running this on the alternator, I liked that idea, essdeezee)
      • directionals (plus hazard toggle)
        
      • headlights
      • brake lights
        
      • reverse lights
      • gauge lights
        
      • *possibly* interior lights (again, I enjoy minimalistic)
        • trunk
          
        • engine
          
        • glovebox
          
        • dome

This is turning out to be a lot like programming. I'll be running my wiring opposite my fuel lines (fuel on driver's side, wiring on passenger's side) with a kick box on the passenger's side with the circuit breakers in it (where a/c would normally go). Someday I may add in some sort of media capabilities to this car, but for now the growl of a v8 is enough to keep a grin on my face all day long.

 

As far as dealers go, I've been looking at http://www.chiefaircraft.com/airsec/Aircraft/InstallationSupply/CircuitBreakers.html with high hopes. They appear to have a wide selection of gear that is directly applicable to my project.

[SteelToad]

... This is turning out to be a lot like programming ...

 

That's what I was thinking when I started planning my rewiring. I'm going to be breaking it down into 4 smaller sections: rear lights, front lights, engine, and dash & accessory.

 

For the rear lights and front (driving) lights, I'm not going to wire at all. What I'm planning to do is to make a small transistor switching unit, (relays for up front) at each end, and then run cat-5 from the brains, to each end. This should simplify things greatly, make finding wiring problems a lot easier, and keep the power at the lights instead of running it all through the car.

 

For the engine electrical, that of course will need sturdier stuff, so it'll be wired more conventionally. The dash will be much easier for me because I'll be using a Dakota Digital all-in-one gauge cluster that'll need only one power lead, but it still needs sensor leads.

[Jesse OBrien]

I really want to use as many stock gauges as possible, and I'm going to see about mending my current dash. That might end up needing to be ditched, but we'll see how it goes.

[SteelToad]

If you decide to ditch it and fully replace it, take a look at Dakota Digital

 

 

Theres a AC control from VintageAire that matches the shape exactly, so it's a no-brainer for me.

[garvice]

Costs won't be vastly different, and as long as the driver (me) is intelligent to NOT immediately and repeatedly flip the circuit breakers if they blow, there should be no more fire hazard than with fuses (correct me if I'm wrong, electrical engineers).

No correction needed. In Electrical designs, fuses are normally used as a cheaper option. Circuit Breakers are used for convenience. You do have to be aware that the tripping curves of circuit breakers and fuses are different. So a 10A Breaker won't always be the same protection as a 10A Fuse. But in general for DC cabling in cars, you shouldn't have to put too much thought into your design.

[Daeron]

Do you have complete wiring schematics for the car from an FSM? I ask regarding the dash wiring. My uncle probably has 73MY pieces for the entire affair, if not a complete 73 dash, that could potentially be pillaged for some sale parts. The dash wiring is completely independent of the rest of the wiring, so it should be easy to re use all or most of it.

 

I am basically going to need to dissect my entire harness and replace the vital wires that need it. I NEED to do at least a minimal job of it to get the car functioning again; if I discover that we have complete 75 wiring pieces somewhere I may just pull a complete stock swap, but step one is dissection of what I have on the car.

 

I've already spliced in a maxi-fuse panel I pilfered from a 94 caddy sedan deville in the boneyard.. Check out the early 90s GM products and beyond for potential junkyard sources of rewiring supplies. The block I used was one of two present in a three block box, the other block was a relay panel IIRC and the entire affair (which shared one common cover) also had a mini ATO fuse panel that attached to IT, and I may end up installing that entire instead of trying to muss iwth my stock fuse panel anyhow. Time will tell on that front.. but many GM products seem to have components worth re-using. Spend and hour or so with a few minimal tools (screwdrivers, one of each, pliers, maybe a 10mm socket, long extension, and ratchet, all 1/4 inch..have more complete tools in your car if you should need em) and explore the GM section of the junkyard, looking at what there is to be had. The pieces are largely classed into 4 or 5 types, and used in many vehicles that I cannot list.. a Cadillac Catera is a particularly unique beast.

 

Theres also a nice relay bracket available on late 80s BMW 3 series:

It has a nice black plastic cover that slides over the entire affair, and is scaleable to house up to five relays, four or five prong type. The plugs are sourceable in many vehicles, including the BMW model listed.