The OBD2 port on your car is how you can connect to your car’s diagnostic system and access your car’s different ECUs. There are several ECUs in modern vehicles, which are more like computers on wheels. This OBD2 port is a 16-pin plug, and we will cover below in the OBD2 pinout what each of the pins in that port does or what it means for different manufacturers.
What is an OBD2 Pinout?
Most modern cars’ OBD2 ports will run standard protocols on the same pins that allow you to read data from the engine ECU and check apparent engine faults. Most countries made into law this standard to allow for emissions testing, etc. You may see several scan tools that say it works on all cars, 1996 and newer cars.
This is correct if you are a car meant for the US market, as they made it law in 1996. However, in other countries like Australia, this was only made into law in 2006. So sellers offering tools targeting only the US market do not entirely understand the scan tools. You will need a full system scan tool for extra access to other ECUs such as Airbag, Body, and ABS.
These use manufacturer-specific codes to access them and may not be on the foremost standard pins of the OBD2 port. That is why you can hear a full system scan tool clicking at times as the relays in the tool change pins, and the software will do the rest of the work to issue the correct commands and headers are sent so that the data and tests you run are accurate.
The OBD Connector
In the above picture, you can see each of the pins and what it does. All the numbers you see are protocols, which the scan tool will use to talk to your car’s ECU. The vendor/discretionary options are open pins that the manufacturer might use for different systems and controls. This pinout will help you do on pre-OBD2 cars. You can work out what protocol they are running and help you choose the correct scan tool and app/software.
An OBD2 port has eight pins in the top row and 8 in the bottom. Each pin has a corresponding use:
1: Used for OEM COMM
2: J1850 Bus + (positive)
3: OEM Reserved
4: Framework/car chassis ground
5: The sensor signal ground is held by this pin
6: OEM COMM (All modern cars might have this pin along with pin numbers 4, 5, 6, 15, and 16)
7: This is the K-line
8: OEM Reserved.
9: OEM COMM
10: J1850 Bus – (negative)
11, 12, 13, 14: OEM Reserved
15: ISO 9141-2 L-line.
16: powers the adapter/scanner
The OBD2 system has five protocols, and they vary per car model. Below are the five protocols and pins you must look for in your OBD2 port to determine if your vehicle is OBD2 and which protocol it runs on. You can also use the OBD2 pinout image above to help you work it out.
SAE J1850 VPW Protocol, used by FORD/GM.
This protocol must have pins 2,4,5, and 16. It has no pin ten, and pin 2 provides the + signal.
SAE J1850 PWM Protocol is used by most cars and FORD.
This protocol must have pins 2,4,5,10, and 16. Pin 2 provides the + signal, while ten is the – signal.
ISO 9141-2, an older protocol found on European vehicles between 2000-2004.
KWP2000/ISO 14230-4, a prevalent protocol found in 2003 and up vehicles (primarily Asian).
This protocol must have pins 4,5,7,15, and 16. Pin 7 provides the K-Line bidirectional communication, and pin 15 is the L-Line unidirectional, which wakes up the ECU. Pin 15 is sometimes optional on ISO 9141-2.
ISO 15765-4/SAE J2480 (CAN) can be found on newer cars. The most modern protocol. Usually found on vehicles made after 2008.
This protocol must have pins 4,5,6, and 14. Pin 6 is CAN high, and pin 14 is CAN low.
More resources on OBD Pinout
You can check out the information-rich wiki here for more reading on what the OBD2 pins mean and how the protocols and PIDs work. The PIDs will show you the general information that all OBD2 cars will show and how it works out the data and displays it.
Using the OBD2 pinout guide above, you can take away the guesswork and determine if your car is OBD2 and which protocol it runs on. All petrol cars made after 2006 and all diesel cars made after 2007 in Australia were mandated by law to be OBD2 compliant. Some earlier cars were OBD2 compliant before this law, and the above guide will help you find out. And if it is not OBD2, do not worry. Just get in touch with us as we have a range of OBD scan tools to help you.
For a rough idea of what tools will do what you can, click on the links below:
Australia 2006+ Car – Basic Scan Tool to access the engine data and clear and check engine faults. This tool here
Australia 2006+ Car – Full system scan tool access all systems to read data and check apparent faults. This scan tool is here.
Pre-2006 and newer cars – Full system scan tool that can do OBD2 and OBD cars. See this tool here.