Scary pic #1. One wire at a time, and double checking my reference documentation, I spliced in the MX-5 ECU connectors to the RX-8 chassis wiring. I generally like to use non-insulated crimp terminals with shrink wrap, so you see a bunch of little sections of black shrink tubing. I did use a couple insulated crimp connectors for the larger wires. I'll probably re-do these in the future, but I didn't have any non-insulated terminals that were large enough.
Scary pic #2. Continuing, one wire at a time. This is fairly challenging, as you want all the wires to be roughly the correct length, so the harness has enough length but not a bunch of long wires that you have to bundle up later.
Believe it or not, this is pretty close to "done."
And, with most of the wires bundled up enough so they're not loosely hanging out. I won't fully wrap the harness until I've got the engine in and have verified everything works, but I've checked every wire a bunch and I believe I've gotten everything correct.
![](https://lh3.googleusercontent.com/MvtSVI_yKCdFTD-k2oXAfI8sOTMu4GzQxKCd__4OD0ozyfo90ioWXfBIs2J5vChTJdVtFczBaaTRFloOBa41MZahMjiuZUeY_pNJW_GHxKIw60uCfQ87jvpdtHiqucOm4cuKb69eF9Cf0BJPGtUW8j0-XoosVvSxXMp-taE6kWKTt5WyrY9ckmak77v7oj8XItnANHyjPlJE-s2sZHDsaCr6ZxFWssH2xK2X-GeGJsZo4r9xcXhknPDdT9RPLslsZJsTd9qVJ19241uFl0Por0Ps6JEKUoQM4cwD_mqbEPKf9OtbTp2WlWZv082K1VYnoCAo_TXBrKPrtnAiSVGi8E3AFBF1eFO-9G858l9of2iV47QR16Td-jdV1Gjz_dJCfaOFuu3V85a6B34S4jIKjtWAb0nhGNkKm8AYZqu24FWcXoWUQTXJlnHGp02vh_I4qtqWflm6cT6Q5zgf82NP39ho6wi2Y9yVngxd1F0ZHJRpQuP7daRW57PbekOygo1NwLeZru8sElEZuCTWnCzC6PGf0LEKRSLR1aoRq3dRpScDLZLN708bLV714trPoS_NZY0NkN7RvKfHO8cJhTeBsz2as0IoBUlLs5eWRVtRIdUzQ4D9kjARrifbzkIA803uSL-8566qZ2We7hALz7LYL0MbseLiuXxE=w1389-h781-no)