What is OBD and How Does It Work in a Vehicle

The OBD is an abbreviation of On-Board Diagnostics used in the Automotive electronic system vehicles which provide the self-diagnostic and reporting capabilities. This is helping the

technician to repair the vehicle without any physical effect and easy to detect the fault is in which module.

Mostly the Diagnostic engineers will be using the term DTC and they will read these DTC from the vehicle and from there they will get the full information about the fault. These DTCs will be stored in the flash memory of the vehicle ECU by On-Board Diagnostic program implemented in the particular ECU.

The OBD is the standard protocol used across most of the light-duty vehicles to retrieve the vehicle diagnostic information from the particular vehicle. In most of the vehicles, there will be one 16 pin connector where the diagnostic engineer supposes to connect their computer system to diagnose the vehicle system. 

This port is a female OBD-II port which mostly available in the below dashboard in front of the driver. Using this port the OEM service engineer can check the vehicle fault and also can flash new ECU software if there is any update or bug fix. Mostly it is used for diagnostic purposes. If there is any fault which you are facing in driving time, then you can go to the service center, and there they will connect a computer or a diagnostic customized computer system to read the fault data are called Diagnostic Trouble Codes. It is nothing like only diagnostic Trouble codes they will read so many different diagnostic data like vehicle speed, engine speed, GPS location, timestamp, snapshot data, and sensor status. After reading all the data they will diagnose on this fault and fix the problem without opening the vehicle like low-end vehicle mechanic.

In the above figure, it is showing different pins of OBD-II port. let us discuss all these pin details.

• OBD-II pin-4 and 5 used for Chassis and Signal ground and the pin-16 for Battery positive terminal power supply. So that the device which you are going to connect with the vehicle can be run using vehicle battery power.
• OBD-II pin-1,3,8,9,11,12,13 is vendor option means if any OEM or you can say the vehicle owner using a different protocol which is not defined in OBD-II standard, then they can use this pin for OEM defined protocol.
• OBD pin-2 & 10 are used for J-1850 serial protocol, the vehicle that used this protocol for inter ECU communication they will have this pin available in OBD-II port for external diagnostic tool communication for vehicle diagnostic.
• OBD pin-6 & 14 used for CAN protocol. Now a day’s most of the vehicles are using this protocol.
• OBD-II pin-7 & 15 used for ISO K-Line protocol.

So in the above, we discussed the OBD-II details for understanding of OBD. Then you would have known what is OBD. so this one of the diagnostic protocols used in the vehicle to communicate with any vehicle and read or write the diagnostic data from or to the vehicle to provide better service to their customer.

In the future, there are so many different types of vehicle technology coming up like Electric vehicles, hybrid vehicles, etc. for which the new standard OBD-III is coming up. No problem I will write a new post on this OBD-III for the understanding of upcoming technology.

I hope you will learn some basic knowledge from this article and please comment on your thought below for inspiration to write more articles on vehicle networking.