The Morey Corporation

A Legacy of Innovation for Good

A Legacy of Innovation for Good

OBD-I to OBD-II: A History of On-Board Diagnostics

OBD-I to OBD-II: A History of On-Board Diagnostics

Working in the transportation industry, you’re familiar with the term On-Board Diagnostics (OBD). But do you fully grasp its importance? On-Board Diagnostics helps technicians, fleet managers, and other professionals better understand a vehicle’s performance. This understanding is vital for gaining a big picture of operations and even fueling effective, timely decision-making.


The team at Morey is on a mission to arm leaders in this space with world-class technology that accelerates growth. Read on as we cover the basic (but important) ideas behind OBD, the history of the systems, and how it can all work to give you a competitive advantage.


Want to learn more about our smart telematics systems and solutions? Connect with us anytime.


What is On-Board Diagnostics?

On-board diagnostics refers to a vehicle’s capability for diagnosing and reporting performance.  An in-vehicle computer system collects information from sensors within the vehicle to regulate activities or alert users of technical problems. 


There are three main components of an OBD system:

  • Electrical Control Unit (ECU) – This is the central unit of the OBD that gathers input from sensors on the vehicle and processes the data to control different parts or monitor issues.
  • Sensors – Examples include temperature, fuel pressure, and oxygen sensors. The sensors then send codes to the ECU and the ECU interprets the signals.
  • Actuators – These are the pieces that convert electrical, air, or hydraulic energy into physical movement. OBD systems can perform actuator tests to assess a vehicle’s performance.


OBD systems have become more advanced, more precise, and more readily available. Over the last decade or so, there have been a few different OBD systems that vary in how much information they provide and how advanced they are. 


Here’s a brief history of OBD systems.


Entering the 1960s vehicles began to employ more technical processes for assessing problems. For instance, rather than listening to engine sounds or smelling a strange scent, engineers relied on instrumentation. 


As the number of sensors and gauges increased, new display devices presented the status and features of the entire electronic system.  Eventually, in 1979 the SAE recommended that all vehicles use a standardized diagnostic connector and specific test signals.



The first step to creating this integrated machine-based diagnostic system came in 1980. General Motors developed and implemented a computerized assembly line diagnostic link (ALDL) that could read out error codes at scale. The first few models used 160 baud rates, while later versions of ALDL could have up to 8192 baud rates. 


The ALDL alerts users of problems using the malfunction indicator light (MIL). However, General Motors’ initial technology didn’t provide context about the nature of the issue, which was a shortcoming that had to be addressed. 


Enter the OBD Systems…



The California Air Resources Board (CARB) made the first push to standardize OBD systems in 1991 when they mandated OBD capability in all cars. The goal was to ensure that all vehicles could detect engine issues and report error codes. 


One thing to note is that OBD-1 was not standardized across manufacturers. This meant that the externally connected tool would typically only work for one make of car and depending on the manufacturer, an OBD-I system will have more or less advanced features.


In addition, the codes themselves weren’t standardized, which meant that two different GM cards could have the same engine problem, but produce completely different codes.


Each manufacturer uses its own diagnostic link connector that can then be connected to different pins. Once these connections are made, a series of codes blink out a number corresponding to a more specific problem.


A simple “check engine” light, for example, will appear the same every time, but when a technician reads the OBD, the two-digit number that appears will help them determine the specific problem that the engine is having.


OBD 1.5

Although not a full update to the existing OBD system, OBD 1.5 was the next step forward in OBD systems. 

Basically, you can think of this as a partial implementation of the OBD-II.


OBD 1.5 included some new or different codes for certain vehicle models and changed the ALDL connections and pins. However, the biggest change was the necessity of an OBD 1.5 compatible scan tool to read the codes generated by the system. 


It was used by General Motors between the years of 1994 and 1995 and was cataloged as either OBD-I or OBD-II at the time. OBD 1.5 can also be found on Mitsubishi 1995 and 1997 vintage, 1995 Volkswagen VR6, and the Ford Scorpio since 1995.



OBD-II became the nationwide standard in 1996. Compared to OBD-I, OBD-II is improved in standardization and capability. The standard OBD-II specifies the diagnostic connector and the corresponding pinout has electrical signal protocols and includes a messaging format.


The scan tool for OBD-II is connected to the vehicle’s battery, eliminating the need for a separate power source, though some technicians do still choose to use a separate source. This is helpful if the vehicle loses electrical power. 


If a car was made after 1996, it most likely has an OBD-II port so an OBD-I scanner won’t work with it. 


Another change between OBD-I and OBD-II is in the trouble codes. OBD-II systems access diagnostic trouble codes for Powertrain (Engine and transmission) and Emission Control Systems. Check out our guide to Diagnostic Trouble Codes, in this guide, we review J1939 & OBD-II DTCs. To look up specific OBD-II codes, refer to this KBB search tool.


In addition, an OBD-II can access vehicle information like the Vehicle Identification Number (VIN), Calibration Identification Number, Ignition counter, and Emissions Control System counters.


On-Board Diagnostic and Vehicle Telematics

The implementation of OBD-II paves the way for vehicle telematics. At Morey, we pride ourselves on offering some of the most advanced OBD-II devices available. Telematics devices like the MCX1 series, are great for simple and quick integration. Some of the advanced features include 4G LTE, crash detection, Bluetooth, and enriched I/Os and GNSS satellite support. It’s excellent for light vehicle tracking in applications such as car rental, courier delivery service, insurance telematics, and more.


For an OBD-II device that is more adaptable, our MCX2 series could be the solution for you, with configurable DIN/AIN, negative input, Bluetooth connectivity, and a backup battery. 


Benefits of OBD-II

From commercial vehicles to fleet management and rental cars, OBD-II systems offer a host of benefits for different industries, such as: 

  • Enhanced Safety – Both the drivers and the fleet benefit from OBD-II systems because by tracking driving patterns, it’s possible to mitigate risks and enforce stricter safety policies.
  • Early Diagnosis – If part of the vehicle is failing, OBD-II will alert you before the situation is dire. This allows you to fix the problem right away and potentially save money on unnecessary maintenance.
  • Flexibility of Installation – It’s simple to connect and install tracking devices with the OBD-II diagnostic port. Whether you’re looking for an MCX101 or an MC4+, your vehicle telematics devices can easily hook up to the OBD-II port.
  • Compatibility – When dealing with an OBD-II car, you don’t need to worry about the make or model because everything is standardized.
  • Reduce Pollution – As The Clean Air Act Amendments (CAAA) recognized, the environmental impacts of motor vehicles cannot be understated. Therefore, the fact that OBD-II systems allow us to track pollutant emissions is a major benefit.


The Future of OBD-II

OBD systems are ever-changing and adapting to make diagnostics easier to understand and more accurate. With each update, OBD systems make it easier for technicians to locate and solve a vehicle’s malfunction. 


While the OBD-II is advanced, it still has limitations. For instance, OBD-II contains 10 standard modes for diagnosing a vehicle’s issues, but this isn’t necessarily enough. The United Nations implemented the World Wide Harmonized on-board diagnostics. (WWH-OBD) as part of the Global Technical Regulations (GTR) mandate. WWH-OBD expands on the current OBD-II standards and adds access to more data types and more detailed fault information. 


Discover Your Partner in Vehicle Telematics

Finding the right OBD-II tracker is essential for monitoring even one vehicle. When it comes to fleet management, this becomes even more important and often necessitates a partnership with a team of IoT and vehicle telematics experts. 


Morey has over 85 years of experience working in this field and our goal is to empower our partners to fulfill their goals. Contact us today to start addressing your connectivity needs together.


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Morey’s blog posts are intended to provide information and encourage discussion on topics of interest to the telematics community at large. Morey is not providing technical, professional or legal advice through these blog posts. While every effort has been made to ensure the information in this blog post is timely and accurate, errors and omissions may occur, and the information presented here may become out-of-date with the passage of time.

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