About the OBD-II Port

OBD-II is the abbreviated term for On-Board Diagnostics II. In modern vehicle, the OBD-II port is usually located in the vehicle cabin, near the driver's side. Look for it below the dashboard or adjacent to the fuse box.

Here are some of the spots you should search for the OBD-II port.

1 To the right of the steering wheel, close to the driver’s right knee.

2 Directly below the steering wheel, on the stock.

3 Somewhere around the base of the stick shifter.

4 Somewhere below the infotainment system.

5 Below the dash on the passenger’s side.

Reporting and self-diagnostics features are the two primary capabilities of a vehicle’s electronic system that a repair technician uses to gain access to subsystem info to monitor vehicle performance and repair it properly. This port is akin to the central processing system of a computer, as it keeps track of the key data points for the vehicle, including mileage, emissions, and speed.

It is connected to the dashboard and will alert the person behind the steering wheel as soon as it detects an issue. The OBD-II port is accessible from within the vehicle on the driver’s side below the dashboard or adjacent to the fuse box. A mechanic or anyone with a specialized tool can read the error codes generated by the engine and presented via the Vyncs device.

Hardware

In India, the presence of the OBD-II port has been mandatory since 2013. The law deems vehicle manufacturing companies to install the OBD-II computer system, which is accessible via the Data Link Connector (DLC). This 16-pin connector tells you about the protocol your car communicates with, depending on the pins populating it.

Important Terminology

Before going through the details, check out some of the keywords used in the protocols.

ECU - Electronic/Engine Control Unit

The ECU may refer to one module or a collection of modules. These form the vehicle’s brain. They monitor and control several functions of the car. They can be standard from the manufacturer, reprogrammable, or have the ability to be daisy-chained for several features.

Some of the most common ECU types

ECM or Engine Control Module:

This element controls the engine actuators, affecting things like air-to-fuel ratios, ignition timing, and idle speeds.

VCM or Vehicle Control Module:

This is yet another module that controls vehicle performance and engine.

TCM or Transmission Control Module:

This one handles the transmission, including items, such as the transmission fluid temperature, wheel speed, and throttle position.

PCM or Powertrain Control Module:

It is a combination of a TCM and ECM that controls your powertrain.

EBCM or Electronic Brake Control Module:

This module controls and reads data from the ABS.

BCM or Body Control Module:

This module controls the vehicle's body features, including power windows, power seats, etc.

DTC - Diagnostic Trouble Code

These codes, defined by the SAE, describe where an issue occurs within the vehicle. They can either be generic or unique to the vehicle manufacturer.

The codes take the following format - XXXXX

The first unit is the error code

Powertrain - Pxxxx

Body - Bxxxx

Chassis - Cxxxx

Class 2 network - Uxxxx

Second digit tells whether the code is unique to the manufacturer or not

x0xxx is for government-required code

x1xxx is for manufacturer-specific code

Third digit shows which system the trouble code refers to

xx1xx /xx2xx show fuel and air measurements

xx3xx shows the ignition system

xx4xx shows emissions systems

xx5xx references speed/idle control

xx6xx deals with computer systems

xx7xx/xx8xx involve transmission

xx9xx notates input/output signals and controls

The fourth and fifth digits show the specific failure code.

xxx00 to xxx99 - these are based on the systems defined in the third digit

PID - Parameter Identification

These are the primary pieces of information you get from an OBD-II system. PIDs are the definitions of the various parameters you may be interested in checking out. They are quite similar to the third digit in the DTCs.
Now, not all PIDs are supported on all protocols, and there can be several unique, custom PIDs for each manufacturer. Sadly, these also are not generally published. As a result, you may need to hunt and/or reverse engineer to determine which system each PID relates to. There are various modes available, with each mode offering PID options in that mode.