Barefootdan's 280z Build

[Barefootdan]

I know I said I wasn’t going to do work on the Z because of the holidays, but maybe this counts as holiday decorticating?😅

 

I felt the bay needed a splash of color 

[Barefootdan]

A few updates since last month. 
 

I’ve been able to find the studs needed to mount the mikuni manifold. Cleaned and painted it as well. Can’t wait to clean up the carbs next. 
 

I’ve been playing around a lot with the 3D printer. I created a faceplate adapter for my switch panel. Slides into my center console and I will be able to screw on the actual switch panel to this adapter via the four screw holes. Looking at original center consoles online, it looks like mine was hacked up for an aftermarket radio at one point so it was missing the upper material. This new adapter should add back in some rigidity. 
 

I also toyed around with some filler plates for the rear bumper. I know the proper way is to weld in blanks, but this was just a fun side project 🙂 they clip in and are fit very nicely! 

 

And then the big project of wiring has started. The engine bay is getting a full new harness, then I am creating adapters to plug into the dash and body harness. Originally I wanted to redo the full body harness as well but all of the connectors inside were fine.

Laying out the harness side by side for lengths.

 

Organized chaos! Luckily, my wife is out of town this week so I’m taking advantage of making the dining room a workshop for a bit.

 
 

Test fitting in the bay before I start adding plugs! So satisfying to see it come together.

 

My little helper!

 

Im about 80% done with the fuse box side of the harness. A few small fused items left to run and then I can start working on connecting the engine bay side. During this I deviated from my original schematics so I will be needing to update that for future reference. I removed my shunt, externally regulated alternator, and all original relays/flashers. I won’t be running my amp meter, instead going for a volt meter. All relays are now modern bosch style, albeit the micro 280 series size to fit within my distribution block. I have a main 125amp circuit breaker in place, continuous duty relay  as a main power trigger, and all new weather pack connectors with GXL wire. 
 

There a few circuits I’m slightly confused on so I’ll need to finish those up in car to trace all of my leads accordingly. Surprisingly I barely used my schematic I made. I used the OEM wiring diagram more often. Maybe I need to trust myself more 😉 

[Av8ferg]

Dan this is an awesome post. If my wife walked in and saw what you did to the dinning room table…..oh boy would it be a bad day for me. I once’s used the oven to back some high temp painted engine parts and she about shot me for that, never saw it the act but smelled it upon coming home
BTW. I have a couple extra stock wire harnesses that connect from the harness behind the dash to the center counsel. If you need one let me know. Got them incase I had issues with the connectors on mine.
Any chance you’d be willing to print up a set of rear bumper plates. Something I thought about but don’t have a printer.


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[Barefootdan]

Thanks @Av8ferg! I will totally print up a set of the bumper plates. One thing I am wondering is, are all bumper cut outs the same size? I only have my '75 to measure. If you get a chance, can you let me know the dimensions of one larger and one of the smaller cutouts? Just want to make sure before I send something that doesnt fit 🙂 

[Barefootdan]

Take whatever time estimate you have for a wiring job and double it 🙂 

So many lessons learned and I cant wait to share them all with you when I am finished. But for now I was working on fixing my turn signal stalk. The PCB board was so brittle that when I disassembled to clean the contacts, it was just falling apart. I was a bit upset that it came apart and I started to look into replacements. I really wanted to keep the OEM stalk and not go aftermarket. Everything was fairly pricey though, so I looked into fixing myself. I found this thread on HybridZ where a toggle switch accomplishes the same function of the OEM switch. A quick print for a bracket and new slider and boom, we're back in business! 

 

The switch in the Off position:

 

Then each direction works flawlessly. It retains the nice CLICK as well.

[Av8ferg]

Dan, you are clearing the trail for me.  My turn signals don’t work either, I haven’t tried to diagnose the problem yet.  I have bigger fish frying right now and the back burner is smoking.  I have too many Z task I’m working on….I’m trying to focus 🧘 .

I look forward to seeing how your repair work out.  I actually get a lot of satisfaction on wiring repair.  As a former USAF avionics mechanic they trained me pretty well in the menial task of building and repairing wire bundles.  Put on a good podcast and get the soldering iron, multi-meter and shrink wrap ready.  

 

 

[Barefootdan]

The wiring saga continues. I started to test each circuit and working my way through one by one. I am trying to diagnose a headlight issue that is stumping me. 
 

When the switch for low beams are on, both lights illuminate nice and bright. When my switch is on for high beam, only my left light is on (dimmer than low beams) and my right light is VERY dim. I am disregarding the fact that high beams are lower than my low beams for now since that is an easy fix on my switch. 
 

I started to trace my wires and check voltages at each connection. With low beams on, both plugs see just under 12V at the low beam and 0V at the high beam. With high beams on, my left light sees 12V at the high beam wire and 0V at the low beam. The weird part is, with the left light plugged in, and I check the right light, I see 12V at the high beam and 4V at the low beam. 
 

I then proceeded to unplug both lights and check continuity as something must be shorting. Right light sees continuity between the high beam and ground. Also continuity between low beam and ground. No continuity between low and high beam wires. The story is different for the left bulb. Continuity between all 3 wires and combinations. Which side is correct? I want to say the right side is correct but it is not illuminating bright enough (could be a bad bulb as well).  
 

My assumption is that I should ONLY see 12V at whichever beam (high/low) is on, never both. 

[Zed Head]

Not clear what you mean by "at the beam".  Power passes from the combination switch, to the fuse box, where it is split in to left and right, each side fused.  High and low beam are determined by which is grounded.  So there should be a power supply wire at each bulb that supplies power to the high filament and the low filament.  The other two wires are ground wires back to the dimmer switch, one high and one low.

I recall that one filament can be burned out but, because it is on a branch with the other, the other can glow dimly as there is a voltage difference across the filament.  Sometimes called backfeeding, I think.  

Anyway, you might try checking resistance across the filaments to be sure none are burned out.  One very dim light and one bright one are often a sign of a burned out bulb (actually one filament in the dim bulb).  

[Barefootdan]

Thanks @Zed Head! "At whichever beam", I meant that if high beam is on, I should see 12v through the high beam wire, low beam on would mean 12v through the low beam wire. Never should I see current in both wires simultaneously. Being that I rewired my entire harness, I am not using the OEM style setup. Rather, I am constantly grounded (not powered) then turn on or off the high/low beam via a relay and power. 

 

It makes sense that there could be backfeed across the filament. I'll go check out the resistance and scavenge for some test lights too. I think my circuit is okay, but the bulbs are throwing me off. The joys of doing a wiring harness before testing every circuit prior to removal 🙂 

[Barefootdan]

Looks like a dead bulb. Two new ones on order!

 

Next, quick question on the operation of the parking lights. How do the front operate with the turn signals? Right now I have both (turn signals in my grill) on (when my headlights are on), then when I use my turn signal, the appropriate side blinks while the other stays on. Is this correct or should the non blinking side be switched off during my turn signal? I question this because it kind of looks like the non-blinking side has some power draw and ever so slightly blinks as well (Brighter when the blinking side is off, Dimmer when on). I am not sure if this is because the car is not running and my poor battery has been powering my project for a couple months now without charge 🙂 

[SteveJ]

The front lights have dual filament bulbs. One filament has a lower light level than the other. If you look in the BE section, you'll see the original bulb spec. It's 1034. I was just looking at some original dual filament bulbs last night.

When you look at the wiring diagrams, you'll see two loops in the bulb where you have a dual filament.

There's also a dual filament bulb on each side of the rear panel.

[Barefootdan]

Thanks @SteveJ! 
That leads me to my next question. I want the parking lights to be on anytime my headlights are on. Is parking light the correct term here? I am referring to the low light filament in my turn signals and taillights your mentioned. 
 

Since I have a toggle switch for my headlights, I initially thought I could route a wire from the output of my relay to turn these on. But i am thinking the this will backfeed between the high and low beams and both will be turned on. My next thought was to use a rectifying diode but my research is leading me to voltage drops (not something I want for my lights!). Is my only choice to place an additional, completely separate, switch to run these light? Similar to the OEM setup. 
 

Sorry for all of the electrical questions lately. I am so close to finishing this harness 🙂 I appreciate all the help.