OBD2 Connector Pinout Configuration
OBD Pins are the individual electrical terminals within the connector of an On-Board Diagnostics (OBD) system, most commonly the standardized OBD-II 16-pin connector found in all cars and light trucks sold in the United States since 1996 and in many other regions globally.
Think of the OBD port as a “data plug” for your car, and the pins are the specific channels within that plug, each designated for a specific purpose, such as power, ground, or a particular type of diagnostic communication.
1. The Standard OBD-II Connector
The connector is a standardized 16-pin (2 rows of 8) female J1962 connector, usually located within the driver’s cabin, near the steering column (under the dash).
Here is the official pinout diagram:
2. Detailed Pin Definitions
While the standard defines the purpose of each pin, not all pins are used in every vehicle. The most critical and consistently used pins are for Power, Ground, and the CAN bus.
Here is a table breaking down the standard pin assignments:
Pin | Signal Type | Description & Function |
1 | Manufacturer Discretion | Reserved for manufacturer-specific purposes. (e.g., GM uses this for the serial data line on pre-CAN vehicles). |
2 | Bus Positive Line | SAE J1850 PWM (41.6 kbit/s) – Used primarily by Ford. |
10 | Bus Negative Line | SAE J1850 VPW (10.4 kbit/s) – Used primarily by Chrysler and GM. |
3 | Manufacturer Discretion | Reserved for manufacturer-specific purposes. |
4 | Chassis Ground | Ground – Direct connection to the vehicle’s chassis (body). |
5 | Signal Ground | Signal Ground – Common ground for the diagnostic signals. |
6 | CAN High | ISO 15765-4 / SAE J2284 (CAN High) – The high-voltage line for the CAN (Controller Area Network) bus. This is the primary diagnostic protocol for modern vehicles (circa 2008+). |
7 | K-Line | ISO 9141-2 / ISO 14230-4 (K-Line) – The serial communication line for many Asian and European vehicles before CAN became dominant. |
14 | CAN Low | ISO 15765-4 / SAE J2284 (CAN Low) – The low-voltage line for the CAN bus. |
15 | L-Line | ISO 9141-2 / ISO 14230-4 (L-Line) – The initialization line for the K-Line protocol (less commonly used than K-Line). |
16 | Battery Power | Switched Battery Power (+12V) – Supplies power to the scan tool from the vehicle’s battery. This is why most OBD-II devices don’t need a separate power plug. |
Key Pins for Modern Vehicles (circa 2008+):
For the vast majority of modern cars, you only need to worry about four pins:
Pin 4 & 5: Ground
Pin 6 & 14: CAN Bus (High & Low)
Pin 16: Battery Power
3. Why the Pin Definition Matters
Standardization: The pin layout ensures that any generic OBD-II scan tool can physically connect to any vehicle. This allows mechanics and DIYers to read basic diagnostic trouble codes (DTCs).
Protocol Identification: The vehicle “talks” using one (or more) of the five possible communication protocols. A scan tool must know which pins are active to communicate correctly. Modern tools automatically detect the protocol.
Device Functionality:
- A basic code reader only needs power, ground, and the CAN bus pins.
- An advanced diagnostic tool might use the manufacturer-specific pins (1, 3, 9, 11, 12, 13) to access proprietary data for specific brands (e.g., BMW, Mercedes-Benz).
- Telematics devices (like insurance dongles or fleet trackers) primarily use pins 4, 5, 6, 14, and 16 to get power and access vehicle data from the CAN bus.
Summary
In essence, the OBD pins are the defined pathways within the universal OBD-II port that provide power, a ground reference, and access to the various diagnostic communication networks used by the vehicle’s computers (ECUs). Understanding which pins do what is fundamental to how all automotive diagnostic equipment works.