My renegade turns over but will not start. It started doing this at -30.

Hello, since you didn't enter data on your geographical location, I can't know if you mean Fahrenheit or Celsius for your temperature. Either way, "fuel line freeze up" is possible, preventing fuel delivery due to ice in the fuel lines. This could be what's happening; first check for fuel pressure at the engine. Other than that, hands on diagnostic testing of engine performance is needed. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops