I have a 93 Mazda Mx-6 automatic 4 cylinder. I am having electrical problems. When I let the car sit overnight or for a day the battery will drain to the point where I cannot start it. We have taken it to a car electrician but they cannot find the problem. They did say that they traced it to the "C" region in electrical schematics. Not exactly sure what that means, but I was told it sounds like a problem with dashboard lights being on. I am not exactly sure if this has to do with the electrical problem but the speed sensor for the car is currently not working.Can anyone help?

 

If they found the "C" region, you'd think they could get closer to the problem... Do all your dashlights work properly? maybe there's a fault in the switch itself...
I don't know if the speed sensor not working would drain the battery, or how it'd effect the dashlights, but I'd suggest getting a new sensor, or known working one, and inspect the wiring to it.