Yep, either that or the main relay failed, fairly common in early Miatas as well. The INJ fuse powers the ECU and a host of other devices.I'm pretty sure that is the case.
Her car spontaneously died so the O2 sensors, throttle position sensor and transmission fluid temp sensor may all have failed.
She did have a mechanic look at it and he most likely checked fuses and relays and everything seems to be working on the dash except the temperature gauge reading max.Yep, either that or the main relay failed, fairly common in early Miatas as well. The INJ fuse powers the ECU and a host of other devices.
I was wondering about that but I didn't know if the sensor ground is even connected to chassis groundThe "ground" return at pin 91 is not the same as chassis ground, BTW. For a quick test one can ground the orange wires to chassis ground to see if there is an open circuit but I wouldn't run it that way; the ground loop created can make the ECU do all kinds of funny things.
Loss of power to the ECU can make engine quit suddenly.