What is the OBD-II Port?

Post Share

If you’re a fleet owner, fleet manager, or even fleet driver, you should know about the OBD-II port. It’s a standardized diagnostic port that allows you to access data from the computer in a vehicle’s engine. GPS trackers can be installed in a vehicle’s OBD-II port to provide live engine and trip data to a central hub or the driver. 

In this article we will outline the basics of OBD-II ports, the history of the OBD-II port, and detailed specs on the OBD-II port pinout. Vehicles are integral to fleets and understanding the OBD-II port is essential to getting the most out of yours. 

What is OBD-II Port? 

So what exactly is the OBD-II port? To start out, let’s break down the abbreviation. “OBD” stands for “on-board diagnostics.” Self-diagnostics and reporting features are two key features provided by the vehicle’s electronic system. This system is used by repair technicians to gain access to subsystem information in order to monitor the vehicle’s performance and properly repair it. 

Light-duty vehicles use on-board diagnostics (OBD) to access the vehicle’s diagnostic information. With the engine control unit (ECU) acting as the “brain” of the vehicle, the OBD is about reducing the diagnostic is produced by the ECU. 

A vehicle’s OBD-II is like a central processing system that keeps track of the key data points for the vehicle, such as mileage, emissions, and speed. It’s connected to the vehicle’s dashboard and will alert the driver if any issues are detected (by turning on the check engine light for example). 

The OBD-II port is accessible from inside the vehicle. It can often be found on the driver’s side, underneath the dashboard. Mechanics (or anyone else with a specialized tool) can read the error code generated by the engine. Looking to install GPS trackers in your fleet vehicles? Check out our comprehensive guide to learn more about where these devices are installed.

History Behind the OBD-II Diagnostic Port 

Early Years of On-Board Diagnostics 

The origins of the OBD-II port began in the 1960s. Some of the organizations involved in the preliminary framework for the standard were the Society of Automotive Engineers (SAE), the California Air Resources Board, the Environmental Protection Agency, and the International Organization for Standardization.

On-board diagnostics systems with the capacity to be scanned to check for issues with the vehicle’s engine were first created by Volkswagen in 1968. Datsun released a very basic on-board diagnostics system more than 10 years later. No other advancements occurred until 1980, when General Motors revealed a proprietary system including interface and protocol that was able to generate engine diagnostics and alert the driver via a check engine light. At the same time, a trend began for other car manufacturers to design and implement their own on-board diagnostic systems. 

Up until this time, before standardization hit the industry, manufacturers created their own proprietary systems. This meant the tools required to diagnose different vehicle’s engines were all different. Things got very complex with each manufacturer using a different connector type, varying the method of electronic interface, and requiring custom codes for reporting problems.

OBD-II Diagnostic Port Standardization  

Finally, on-board diagnostics began to standardize in the late 1980s. This first occurred in 1988, when Society of Automotive Engineers recommended that manufacturers follow the same set of diagnostics and start using a standard connector pin. 

OBD-I was mandated in 1991. California decided all vehicles should have on-board diagnostics. This was a precursor to the OBD-II port. 

OBD-II was created three years later, in 1994. In that year California required all vehicles sold (starting in 1996) to have on-board diagnostics as had been previously recommended by SAE in 1988. This was the advent of OBD-II, and was introduced into legislation primarily to perform across-the-board emissions testing on vehicles. Due to California’s legislation, in 1996 car manufacturers started to install OBD-II ports in all cars and trucks across the country.

OBD-II introduced standardized diagnostic trouble codes (DTCs) that accounted for the fact that different protocols have signals specific to their vehicle manufacturer. There are five basic signal protocols:

  • ISO14230-4 (KWP2000): Keyword Protocol
  • ISO9141-2: Used in all Chrysler vehicles
  • SAE J1850 VPW: Variable Pulse Width 
  • SAE J1850 PWM:  Pulse Width Modulation
  • ISO 15765 CAN: Controller Area Network (used in all vehicles made after 2008)

In-Depth: OBD-II Diagnostic Port

The OBD-II port pinout gives access to the engine’s status information and Diagnostic Trouble Codes. The DTCs cover a number of aspects of the vehicle including powertrain (engine and transmission) and emission control systems. The OBD-II pinout also provides further information including the vehicle identification number (VIN), Calibration Identification Number, ignition counter, and emissions control system counters. 

A computer system contains all these DTCs, since these codes vary between manufacturers. There are trouble codes for a wide range of aspects of the vehicle including powertrain (including engine, transmission, emissions), chassis, body, and network. The list of standard diagnostic trouble codes is extensive. 

Standardized scanning tools make identifying issues much easier these days. A fleet vehicle can be scanned for its error code when it’s brought to a shop to be serviced, and this will help the mechanic solve the problem much more quickly. The OBD-II port lets mechanics accurately diagnose issues with your fleet’s vehicles, inspect them promptly, and fix any issues before they become major problems. Ultimately the OBD-II port helps get your fleet vehicles back on the road faster and stay there longer.

Detailed Look: OBD-II Port Pinout

Standardized printouts make it possible for all OBD-II scanning tools to read DTCs. Scanning tools have the capacity to read from any of the 5 protocols. The standardized OBD-II port pinout is as follows:

Pin 1: Utilized by manufacturer

Pin 2: Utilized by SAE J1850 PWM and VPW

Pin 3: Utilized by manufacturer

Pin 4: Ground

Pin 5: Ground

Pin 6: Utilized by ISO 15765-4 CAN

Pin 7: ISO 14230-4 and The K-Line of ISO 9141-2

Pin 10: Utilized solely by SAE J1850 PWM

Pin 14: Utilized by ISO 15765-4 CAN

Pin 15: ISO 14230-4 and the K-Line of ISO 9141-2

Pin 16: Power from the vehicle’s battery

Your fleet vehicle's OBD-II ports may be small but they can play a big role in helping your fleet succeed. To learn about what OBD-II ports can be used to help your fleet succeed check out Azuga Fleet. This smart fleet tracking software will allow you to take your company to the next level without the growing pains.