I am investigating the possibility of monitoring and controlling the car cabin temperature using GPRS. I will be using Arduino Uno and GSM shield to communicate with an Android App. The arduino works as a bridge between the mobile app and the car. I initially thought i can achieve this by connecting arduino to the OBD-II through ELM327 but apparently it is not possible. Do I need to do some physical wiring to be able to start the car and switch on/off the ventilator or the A/C?