Ok guys, first ill introduce myself. My name is Matt, i just picked up a miata as a toy/extra car. Ran my own shop for almost 2 years, owned a whole variety of cars over the years.

Ok so i picked up a 91 miata that was turboed, MS, and blown up. Toss in a stock good running 1.6. The factory harness/under the dash was one of the biggest wiring nightmares i have ever seen. everything was hardwired straight to power, absolutely NO relays existed under the dash, 254,931 stupid gauges and lights, custom power windows harness, "custom" rear speakers, etc. Any got the entire harness fixed and back to 100% stock except 1 wire i cannot figure out! I have physically been through the entire harness, FSM, and wiring diagrams 50x and dont see a place for this wire. Common sense matching the colors tells me its a sensor ECU ground of sort, but noo idea where it goes. It was twisted up with the shielding from the two red wires that become covered with a orange and grey sleeve. I will post pics and let me know what you think or can see on yours.

 

Am I supposed to be looking at the black one with the red dots or one of the other ones?

 

sorry for not clarifying yes the wire in question is in the first picture. The black with light green and red dots. I know its a sensor ground within the harness, what im stuck on is that the ecu has 2 sensor ground inputs, and both are there and intact......going to pickup a unmolested factory harness today to compare and probably swap

 

It looks like the two black/lt. green go right where you have them next to the two black ones in connector 2 positions C & D.

https://www.miataforumz.com/1990-200...ing/91diag.pdf