Hey everyone, recently had an (apparently common) issue with my NA transmission where it became stuck in reverse. I managed to fix when I had it out and when I placed the tranny back in, I can't get into reverse at all and when I shift into 5th, the reverse back up lights come on. All the other gears are available but no reverse. I thought it may have been wiring but that's all fine.... Any thoughts?

 

Anyone?

 

Could be debris in your turret oil for you getting locked out of reverse, and there are plenty of guides on how to remedy this (hint: turkey baster.)As for 5th turning on the reverse lights, there's a notch on the 5th/R shift rod claw that activates the reverse light switch. When the rod moves forward to engage reverse, there's a steep slope that depresses the switch. When the shift rod moves backward to engage 5th, there's a shallower slope that normally wouldn't depress the switch. If the switch were sticking too far into the housing and missing the washer, it would get pressed slightly in 5th as well. You can pull the switch out and go to your local auto parts store and find a drain plug crush washer that fits.
^This is NA Miata information, but I have a strong hunch it would hold true for your FC.
Good luck!