Most OBD1 US cars use the 12pin ALDL connector shown beside. If you have a car with the 12 pin connector this is the Interface for you ! Some older cars (such as early TPI's like GM 1227165 ECM, 1986-89 5.0 and 5.7 V8's) will require a 10Kohm resistor to be plugged in between pins A and B on the 12 pin ALDL connector in order to put the car into "ALDL mode" and have the serial data start flowing. Our Interface have a slide switch which can set pin B to different modi like connect pins A & B directly, by 10K Ohm or keep them completely disconnected. - Connects to RS232 - Power LED - Robust casing - Slide switch for change modi of pins A & B - Uses reference levels for high/low signals so works on all cars without problems not like some homemade interfaces - Uses Motorolas MC33199 Transceiver at 5V ALDL levels not some homebrew solution - Dual powered (can take power from RS232 handshake lines or over 12V cigarette lighter connector cable what makes it superior over all other ALDL interfaces on market) - ALDL Interface with 12pin plug - 12V cigarette lighter connector to 2,1mm DC plug cable - RS232 extension cable