well, my reverse lights arent working, and since its both of them, im guessing its not a short. where is the switch for it? on the tranny somewhere? looked at the haynes manual but it was worthless. also, for some background the previous owner swapped the engine and transmission, and did an overall half-assed job with it. so its very possible he just didnt connect it.

 

The reverse switch is screwed into the left rear of the tranny. If you look under there and see something with wires coming out, that's it. It has a little nipple-like button switch that gets pressed when you shift into reverse. The wires need to be connected properly for the reverse lights to work. I have the same problem as you right now, but my switch itself is bad. If you get the FSM, it shows where the backup switch goes, and the wiring diagram tells you what color wires plug into what. Hope this helps.

Anyone have a backup switch for sale???

 

You may wish to search on this, as it has been covered before...

But it is common to have the reverse switch fail on the FC and Miata, so you will need to locate and test the switch before moving ahead.

If it is the switch, I and several others have had good luck using a relay to boost the reverse signal/current capability of the switch.

If it is not the switch, yes you will need to check the wiring going to the tranny.

 

there are two single wires at the tranny, accessable from under that car that connect to two single red wires.

this might have come loose.

check it.