Did you know that your car has a mind or let me say a memory of its own? If you own a car that was made in the last 20 years, then there is a way to ask your car what is wrong with it if it is feeling sick.

Gone are the days when solution to a fault in a vehicle can only be rectified via troubleshooting, you can imagine the stress that would be involved and eventually, the problem source might not be discovered or another problem created in the process. Thanks to technology, problems and problem sources can easily be identified in a vehicle by the use of ON-BOARD DIAGNOSTICS (OBD).

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As promised in my last post, I would be discussing another awesome aspect of automobile maintenance and repair engineering which I was opportune to learn during the period of my industrial attachment at Mandilas Auto.

I remember first day I encountered the process of automobile scanning. It was during my early days as an intern in the workshop. As a young mechanical engineering student, I was amazed when on that fateful day, the head technician in the workshop walked past me carrying a device that looked like a tablet with a cord attached to it and he approached a vehicle telling the other technician he wanted to perform a scan! Of course I knew what a scan meant but I wasn’t sure of how it was done and this caught my curiosity. Fortunately for me, I was not busy at that moment so I quickly moved closer to him in an effort to assist him and learn in the process. Beautiful memories I must say!

In this article, I would be discussing the following

ON-BOARD DIAGNOSTICS
HISTORY OF THE OBD
COMPONENTS OF THE OBD
OBD-I AND OBD-II
OBD scanners
HOW TO CARRY OUT On-Board Diagnosis

WHAT IS ON-BOARD DIAGNOSIS?

On-Board Diagnostics (OBD) simply put, is a medium through which your vehicle reports its status to you! It refers to a vehicle’s self-diagnosing and reporting ability.
The OBD is equipped with the ability to report to the owner or technician, important information about the vehicle’s systems and subsystems. Has your car ever displayed a warning light or simply a check light on the instrument panel? Then that’s your car’s OBD at work.
The OBD is also equipped with a port through which a technician can connect an external computer to communicate with the car’s computer (remember the device I told you about?).

HISTORY OF THE OBD

OBD was first introduced in response to a ruling by CARB (California Air Resources Board) that all vehicles under 14,000 lbs. sold in California be equipped with on-board diagnostic systems. According to Wikipedia, the early versions of the OBD were known to simply flash a malfunction indicator light or idiot light.
OBD initially came as a result of two factors: there was a need to regulate the emissions and the adoption of the electronic fuel injection technology by automobile manufacturers in the 1980s. as time went on and technology advancement increased, the OBD technology was made to apply to almost all subsystems of a vehicle.

As of today’s world, a modern vehicle can support over hundreds of parameters accessible via the DLC using special tools known as scan tools

COMPONENTS OF THE OBD

The basic constituents of an OBD system include;
• The ECU (Electronic control Unit) which is your car’s in built computer which controls all sensors and actuators in your vehicle

• SENSORS which as the name implies, sense the present condition of the system or subsystem which they are attached to

• ACTUATORS which are responsible for carrying out the commands from the ECU

• MIL (Malfunction Indicator Light) which is the display you see on your dash board

• DLC (Diagnostic Link Connector) which is the port where your technician connects the diagnostic tool to locate the particular source of the issue which caused the MIL to turn on

The modus operandi of the system is summarized in this short story;
You wake up in the morning and start your car ready for work as usual. Unknown to you, your car engine has encountered a little problem while working hard on the long drive of yesterday the SENSOR “senses” a malfunction or irregularity in the subsystem, it sends a signal to the ECU, the ECU in turn interprets this signal and commands the ACTUATOR to perform a task or adjust a parameter in order to correct the issue. If the issue persists or aggravates either due to repeated, unhealthy or impossible adjustments, the ECU causes a MIL to come on. You notice the MIL and don’t understand what it means or what went wrong and you put a call through to your technician. The tech. guy comes to your house and connects an OBD scanner to the vehicle via the DLC port and tells you what went wrong and also bills you for it. You have no choice but to pay him and he fixes your car….and everyone lives happily ever after.

PICTURE OF ONE OF THE DIAGNOSTIC TOOLS I USED

OBD-I AND OBD-II

I am sure some of us are familiar with the term OBD-II and might have wondered if there was an OBD-I and what difference lies between them. Well, here us the major difference that exists;
OBD-I is actually the first generation of OBD systems which were available in the 1980s. These systems were totally unique to every vehicle and as a result, a technician would need a different tool for every different vehicle make. After a while. OBD-I systems supported various makes but they were supplied with an array of different adapter cables.
OBD-II was made as a result of a new set of regulations set by the Society of Automotive Engineers (SAE) and International Standardization Organization (ISO) in order to bridge the obvious gap.

All OBD-II compliant vehicles were required to use a standard diagnostic connector (SAE J1962), and communicate via one of the standard OBD-II communication protocols.
The OBD-II systems were first introduced in the tear 1994 and they became a compulsory requirement for all cars and trucks starting from the year 1996
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OBD SCANNERS

The ECU usually stores the problems it records in form of alpha numeric codes. A single MIL might mean more a different error at different times, therefore, the problem cannot be diagnosed by mere interpreting the MIL. In order to access the information stored by the ECU, a scanner needs to be connected to the vehicle via the DLC. This scanner then reads the codes and sometimes, depending on the type of scanner. The codes are interpreted.
The codes sometimes are not the same across all vehicles but some manufactures use some common codes, the interpretation of the codes can be seen here
There are different types of OBD scanners available today ranging from hand held scan tools, mobile device based tools to PC based scan tools and analysis platforms. They all perform the basic function of sourcing and displaying the error codes stored. Although the ones with higher specification are equipped with programs which enables live monitoring and analysis of performance of the vehicle. Simple scanners are available all over the market.

DLC source wikimedia commons

HOW TO CARRY OUT On-Board Diagnosis

While I was an intern, I was able to carry out diagnosis of vehicles using OBD scanners and here is the procedure

1. The scanner cable is connected to the vehicle’s DLC port (the DLC port is usually directly under the dashboard for most car makes).
2. The engine is started and allowed to run.
3. Depending on the type of diagnosing tool used, the vehicle make, model, and (or) year are selected to access the various scanning options available.
4. To view trouble codes, the system in question is selected; i.e. engine, power train, chassis or body.
5. The option to view the trouble codes is selected and the list of trouble codes (and interpretation, depending on the type of scan tool used).
6. The trouble codes can be printed for further analysis
7. If the problem has been rectified, the option to clear trouble codes is selected so as to remove the ‘malfunction indicator light”.

A SCANNER SHOWING ERROR CODES AND INTERPRETATION

When next you see that funny or strange indicator light blinking or permanently ‘on’ on your dashboard panel, I advise you to take it to a diagnostic technician to help check what is wrong. Also it is wise to always insist on a diagnosis before any repair operation is done, this is to prevent being ripped off or issues that may arise as a result of guesswork.
It is not a bad idea to have an OBD scanner of your own, you never can tell when you would be needing it. Just make sure it displays a language you can read.

CONCLUSION
I would always say that technology is shaping the lives of humans and this one is not an exception. You would agree with me that technology has gone further to provide vehicles that have minds of their own. I hope I have once again been able to share my experience as an automobile technician intern and also educated you about how the OBD operates.

REFERENCES
ON BOARD DIAGNOSTICS | WHAT IS OBD? | A LOOK AT OBD | From dongles to diagnostics, here’s all you need to know about OBD/OBD II |OBD CODES