My 1992 Miata has had a bunch of wiring issues since I've owned it due to a previous owner's carelessness when doing a 1.8 engine swap. Last year i fixed all i knew of at the time, but alas there were things i missed. i decided the only way to fully know if i managed to fix everything would be to remove the full harness, deloom it and repair/replace anything i find that looks suspicious. I also wanted to take this as an opportunity to do a wiring tuck since I've never done it before.

Step 1 was disassembling and removing the harness.this wasn't really that bad, but it was tedious. The pro move was removing all the interior to do this. I'm sure it could have been done with some of it still installed, but removing it doesn't take that much time or effort and makes this job much easier.



here's a shot of the entire harness removed, getting ready to be deloomed and stripped of all things that aren't required.


Mid deloom. my workflow went something along the lines of:
1) select connector at random
2) deloom it
3) trace out wires, decide if it is required for operation.
4) remove any unneeded wires. ( i only depinned connectors, i have cut exactly ZERO wires )
5) goto(1)



I started from the driver's side since i knew i was going to remove most of everything on that side. It was at this point where i began to question if i would ever get this reassembled completely.

this is a 17 gallon tub of wires that were removed from the OEM harness.


getting ready for a test of all the accessories (everything but the engine). Handling the harness at this point was what i imagine iphone headphones in a pair of jeans' pocket is like. Any tiny misstep would cause the harness to become annoyingly tangled amongst itself. To transport it between my house and the garage, i draped it over my shoulder and wore it like a really ugly scarf.



After wrestling the beast into the car again, i fed the unorganized mess that remained after the great trim and tested every peripheral and accessory. Previous to this job, many things in this car did not work, or didn't work correctly including but not limited to brights, horn, AC, ABS, cruise, and the brake light on the dash to name a few. After this, all of those systems either worked or were removed.



After confirming that everything worked correctly (what a relief), i expanded a couple holes that already existed in the fenders and fed the harness through. I didn't want to have to depin the connectors while i was feeding them in/out doing test fits, so i made them a bit bigger than they needed to be. I now regret this and plan on making a bracket that has a grommet through it for the holes that will secure the harness in its place.



Since i was building a new engine harness from scratch, i figured now was a good time to finally mount my flex fuel sensor. I've been running flex fuel in this car for about a year now, but the sensor was previously just flopping around in free space. Since i removed my ABS system during this time, i took advantage of the new free space on the old bracket. I've since cleaned this up a bit more and also used this to mount my GM MAP sensor. The bracket still has a few unnecessary mounts and extra metal that i'm going to trim up once i know everything else is mounted securely.




I also decided now was a good time to switch to coil on plug, so i made a bracket for the Toyota COPs that have been sitting in my new parts bin for a year.



And the completed bracket. I'd been dreading this for months and in reality it took less than an afternoon (after i failed the first attempt that is )



Rather than try to cut/extend/repair my existing harness, i decided id just spend the extra $ and build a new one from scratch. This eliminated any possibility of the previous owner screwing me over again. (now i only have to worry about myself screwing me over)
I've done this job on a few different cars before, so at this point i was feeling more confident than i was about the wiring tuck. This should have been as simple as running the harness, then joining the two harnesses together inside the car somewhere. Of course with all of my modifications, it wasn't that easy, but alas the job ended up being completed.



This is more or less the "final" location of all the wires. much of it is still without covering, and there were a few bodges i had to make once i tested it.





and finally, the interior while testing and fixing my mistakes. This is how the car currently sits. It runs very well on the new harness, new sensors and new ignition system, but there's obviously still work to do. most of the chassis harness is complete, but as i said earlier, i had to fix a couple mistakes, so those need to be finalized. then the harness needs to be wrapped, and routed in it's final location. the engine harness is also still almost completely uncovered with the exception of some tape holding it's basic shape.




Well i hope someone finds some use in this. I still have a bit of work to do obviously, but the gist of it is that with enough terrible decisions and time, I can have something that functions exactly the same as it did before all the work, but at least i can sleep at night knowing the next time something doesn't work in this car, i'll know it isn't the previous owners fault directly anymore.