The On-Board Diagnostics II (OBD-II) port is a crucial interface in modern vehicles, acting as the gateway to your car’s computer systems for diagnostics, monitoring, and even performance tuning. Understanding the Obdii Port Pinout is essential for anyone involved in automotive repair, diagnostics, or vehicle data analysis. This article provides a comprehensive guide to the OBD-II J1962 connector pinout, outlining the function of each pin and its role in vehicle communication.
Decoding the SAE J1962 OBD-II Connector
The standardized OBD-II connector, officially known as the SAE J1962 connector, is a 16-pin interface that provides access to various vehicle communication protocols and power. This standardization ensures compatibility across different makes and models, making it easier to diagnose and service vehicles. However, the specific function of each pin can vary depending on the vehicle manufacturer and the communication protocols they implement.
There are two main types of J1962 connectors defined: Type A and Type B. The primary difference lies in their voltage specifications, catering to different vehicle electrical systems.
SAE J1962 Type “A” Connector (12V Systems)
The Type “A” connector is the most common, designed for standard 12V automotive electrical systems found in passenger cars and light-duty trucks. It’s the interface you’ll typically find under the dashboard on most consumer vehicles.
SAE J1962 Type “B” Connector (24V Systems)
The Type “B” connector is designed for 24V electrical systems, commonly found in heavy-duty trucks and commercial vehicles. While physically similar to Type A, it operates at a higher voltage and has different power specifications.
OBD-II Connector Pinout Details: Pin by Pin Description
To effectively utilize the OBD-II port, understanding the function of each pin is crucial. Below is a detailed OBD2 pinout table, outlining the standard and manufacturer-specific assignments for each pin in the J1962 connector.
Generic OBD-II Pinout (SAE J1962 Standard)
| Pin Number | Description |
|---|---|
| 1 | Manufacturer Discretionary: Often used for manufacturer-specific communication or control functions. |
| 2 | SAE J1850 Bus + (VPW / PWM): Used for SAE J1850 Variable Pulse Width Modulation (VPW) and Pulse Width Modulation (PWM) communication protocols, common in older GM and Ford vehicles. |
| 3 | Manufacturer Discretionary: Similar to Pin 1, this pin can be assigned for proprietary manufacturer uses. |
| 4 | Chassis Ground: Provides a ground connection to the vehicle chassis, ensuring electrical grounding for diagnostic tools. |
| 5 | Signal Ground: A dedicated ground for signal circuits, helping to minimize electrical noise and ensure clean data transmission. |
| 6 | CAN High (ISO 15765-4 and SAE J2284): The high signal line for the Controller Area Network (CAN) bus, a high-speed communication protocol widely used in modern vehicles for engine management, diagnostics, and other systems. |
| 7 | ISO 9141-2 / ISO 14230-4 K Line: Used for ISO 9141-2 and ISO 14230-4 (Keyword Protocol 2000 – KWP2000) communication protocols, older standards still found in some vehicles, particularly European models. |
| 8 | Manufacturer Discretionary: Another pin available for manufacturer-specific functions, which can vary significantly. |
| 9 | Manufacturer Discretionary: Like Pins 1, 3, and 8, this is reserved for manufacturer-defined purposes. |
| 10 | SAE J1850 Bus – (PWM-only): The low signal line for SAE J1850 PWM communication, complementing Pin 2. |
| 11 | Manufacturer Discretionary: Continues the trend of manufacturer-configurable pins, offering flexibility in vehicle system design. |
| 12 | Manufacturer Discretionary: Provides further options for manufacturers to implement custom features or diagnostics. |
| 13 | Manufacturer Discretionary: Offers even more flexibility for manufacturer-specific implementations. |
| 14 | CAN Low (ISO 15765-4 and SAE J2284): The low signal line for the CAN bus, working in conjunction with Pin 6 to facilitate CAN communication. |
| 15 | ISO 9141-2 / ISO 14230-4 L Line (Optional): The L-Line for ISO 9141-2 and ISO 14230-4 protocols. Often optional and not always implemented. |
| 16 | Vehicle Battery Power: – Type “A” 12V/4A – Type “B” 24V/2A: Provides direct battery power to the diagnostic tool, allowing it to operate and communicate with the vehicle’s systems. Note the different current ratings for Type A and Type B connectors. |
It’s important to note that while the obdii connector pinout is standardized, manufacturers can and do utilize the “Manufacturer Discretionary” pins (1, 3, 8, 9, 11, 12, 13) for various purposes. This can include:
- Proprietary Diagnostic Functions: Accessing manufacturer-specific diagnostic codes or routines beyond the standard OBD-II protocols.
- Control Signals: Implementing control functions for vehicle systems, such as activating specific tests or features.
- Communication with Specific Modules: Establishing communication with particular vehicle modules beyond the standard OBD-II network.
- Alternative Communication Protocols: Utilizing different or additional communication protocols for specific vehicle functions.
Examples of Manufacturer-Specific Pinout Variations
To illustrate the variations in OBD port pinout implementation, consider these examples of how manufacturers might use discretionary pins:
(Example 1: Enhanced Diagnostics)
| Pin Number | Description |
|---|---|
| 1 | Switched +12V Ignition Signal: Provides an ignition-switched power signal, useful for tools that need to know when the ignition is on. |
| 2 | Unused (or unknown) |
| 3 | Ethernet RX+ |
| 4 | Chassis Ground |
| 5 | Signal Ground |
| 6 | CAN High (ISO 15765-4 and SAE J2284) (500Kbps) |
| 7 | ISO 9141-2 / ISO 14230-4 K Line (10.4Kbps) |
| 8 | – Secondary K Line for Body/Chassis/Infotainment Modules – Ethernet Enable (via 510 Ohm, 0.6 Watt resistor to battery voltage) |
| 9 | TD (Tachometer Display) Signal / Engine RPM Signal |
| 10 | Unused (or unknown) |
| 11 | Ethernet RX- |
| 12 | Ethernet TX+ |
| 13 | Ethernet TX- |
| 14 | CAN Low (ISO 15765-4 and SAE J2284) (500Kbps) |
| 15 | ISO 9141-2 / ISO 14230-4 L Line (10.4Kbps) (Optional) |
| 16 | Vehicle Battery Power: – Type “A” 12V/4A – Type “B” 24V/2A |
In this example, Pins 1, 3, 8, 9, 11, 12, and 13 are repurposed for features like ignition signal, Ethernet communication, and secondary K-line access for body/chassis modules. This demonstrates how manufacturers extend the functionality of the OBDII port.
(Example 2: GM Specific)
| Pin Number | Description |
|---|---|
| 1 | – Single-Wire CAN (SAE J2411 / GMW3089) (33.3Kbps) – GM UART / ALDL (SAE J2740) (8192 bit/s) |
| 2 | SAE J1850 VPW Bus + (10.4Kbps) |
| 3 | Object Detection CAN Bus + |
| 4 | Chassis Ground |
| 5 | Signal Ground |
| 6 | CAN High (ISO 15765-4 and SAE J2284) (500Kbps) |
| 7 | ISO 9141-2 / ISO 14230-4 K Line (10.4Kbps) |
| 8 | Manufacturer Discretionary |
| 9 | GM UART / ALDL (SAE J2740) (8192 bit/s) |
| 10 | Unused (or unknown) |
| 11 | Object Detection CAN Bus – |
| 12 | Chassis High-Speed CAN Bus + (500Kbps) |
| 13 | Chassis High-Speed CAN Bus – (500Kbps) |
| 14 | CAN Low (ISO 15765-4 and SAE J2284) (500Kbps) |
| 15 | ISO 9141-2 / ISO 14230-4 L Line (10.4Kbps) (Optional) |
| 16 | Vehicle Battery Power: – Type “A” 12V/4A – Type “B” 24V/2A |
Here, Pin 1 is used for Single-Wire CAN and GM UART/ALDL protocols, Pin 3 and 11 for Object Detection CAN, and Pins 12 and 13 for Chassis High-Speed CAN. This highlights the diverse applications of discretionary pins for brand-specific communication networks within the vehicle.
(Further Examples in Original Article – Tables 6-16 can be considered as additional examples, but for brevity, not included here. They are repetitive and don’t add significantly to the core explanation of pinout concept)
Why Understanding the OBD-II Port Pinout Matters
For automotive professionals and enthusiasts, a solid grasp of the OBDII port pinout is invaluable for:
- Accurate Diagnostics: Ensuring correct connections for diagnostic tools to read data and communicate with vehicle systems effectively.
- Custom Modifications: Developing or implementing custom vehicle modifications that require interfacing with the vehicle’s communication network.
- Data Acquisition and Analysis: Setting up data logging systems to monitor vehicle performance and behavior for analysis and tuning.
- Troubleshooting Communication Issues: Diagnosing problems related to vehicle communication networks by verifying pin integrity and signal presence.
- Developing Automotive Electronics: Designing and testing new automotive electronic devices that interact with vehicle systems via the OBD-II port.
Conclusion: Your Key to Vehicle Communication
The OBD-II J1962 connector and its obdii port pinout are fundamental to modern automotive diagnostics and vehicle communication. While the standard provides a common framework, understanding the potential variations and manufacturer-specific implementations is crucial for anyone working with vehicle electronics. By referencing this guide and the detailed pinout information, you can confidently navigate the complexities of the OBD-II port and unlock the wealth of data and diagnostic capabilities it offers.
For any errors or suggestions regarding this information, please contact [email protected]. Copyright © 2018 DashLogic, Inc. All Rights Reserved.
