I just realized.... My tesla has a resistance reading function. Why does it read 0.0 ohms? Shouldn't it tell me at least if it is below 1.3? or am i wrong?
It will. If you have the display set to, say, display volts or watts when you fire and you put a 0.5 ohm coil on it, if you try to fire it the display will show the resistance of the device instead. (And refuse to fire, of course.) If you just use the resistance check function it will display the resistance of anything it finds attached, whether or not it's built in protection would refuse to fire it.
If you are getting 0.0 ohms on a Tesla that's a shorted device to a Tesla. 9.9 ohms is an open device or no device at all.