What is the function of the OBDII connector pins?
The 16 pins of the OBDII connector each have their specific functions, as follows:
Pin 1: Usually customized by the manufacturer. For example, General Motors may use it for J2411 GMLAN/SWC/SingleWire CAN communication.
Pin 2: It is the positive signal for SAE J1850 PWM (pulse width modulation) or SAE J1850 VPW (variable pulse width) communication. If the vehicle does not use these communication protocols, they will be customized by the manufacturer.
Pin 3: Generally defined by the manufacturer according to their own needs.
Pin 4: It is the body ground and electrically connected to the vehicle chassis, mainly used to provide power grounding for external testing equipment.
Pin 5: As a signal ground, it provides grounding for communication transceivers and testing equipment, while reducing noise and voltage offset.
Pin 6: If the vehicle uses CAN communication, this pin is the CANH signal; If CAN communication is not used, it will be customized by the manufacturer.
Pin 7: If using ISO 9141-2 or ISO 14230-4 single or double line communication, it is a K-line signal; If these communication protocols are not used, they will be customized by the manufacturer.
Pin 8: Its function is usually defined by the vehicle manufacturer themselves.
Pin 9: Its use is usually determined by the manufacturer themselves.
Pin 10: When using SAE J1850 PWM communication, it is a negative signal. If this protocol is not used, it will be customized by the manufacturer.
Pin 11: It can usually be defined by the manufacturer based on specific circumstances.
Pin 12: The function of this pin is generally defined independently by the vehicle manufacturer.
Pin 13: Its function is usually set by the manufacturer themselves.
Pin 14: If the vehicle uses CAN communication, it is a CANL signal; If CAN communication is not used, it will be customized by the manufacturer.
Pin 15: If using ISO 9141-2 or ISO 14230-4 two-wire communication, it is an L-line signal; If these communication protocols are not used, they will be customized by the manufacturer.
Pin 16: Provides permanent positive voltage for external diagnostic testing equipment, typically 12V or 24V, depending on the vehicle type. It supplies power to connected devices and can serve as a reference for K-line communication.
