The OBD2 port on your car is how you can connect to your car’s diagnostic system and access your car’s different ECU’s. There are a number of different ECUs in modern cars and they 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 manufactures.
On most modern cars the OBD2 port will run some standard protocols on the same pins that allows you to read data from the engine ECU and check and clear engine faults. This is a standard that has been made law in most countries to allow for emissions testing etc. You may see a number of scan tools that will say it works on all cars 1996 and newer. This is correct if you are a car that was meant for the US market as they made it law from 1996, but in other countries like Australia it was only law from 2006. So these tools are normally sold by a seller that is targeting the US market or does not have a full understanding of the scan tools. For extra access to other ECUs such as Airbag, Body, ABS and etc. you will need a full system scan tool. These use manufacturer specific codes to access them and may not be on the main 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 right commands and headers are sent so that the data and tests you run are correct.
In the above picture you can see what each of the pins is and what it does. All the numbers that you see are protocols and this is what 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 extra systems and controls. What this pinout will help you do is on pre OBD2 cars you can work out what protocol they are running and this can help you choose the correct scan tool and app/software.
An OBD2 port has 8 pins at the top row and 8 at the bottom row. Each pin has a corresponding use:
Pin 1: Used for OEM COMM.
Pin 2: J1850 Bus + (positive).
Pin 3: OEM Reserved.
Pin 4: Framework/car chassis ground.
Pin 5: The sensor signal ground is held by this pin.
Pin 6: OEM COMM. All modern cars might have this pin along with pin number 4, 5, 6, 15 and 16.
Pin 7: This is the K-line.
Pin 8: OEM Reserved.
Pin 9: OEM COMM
Pin 10: J1850 Bus – (negative)
Pin 11, 12, 13, 14: OEM Reserved
Pin 15: ISO 9141-2 L-line.
Pin 16: powers the adapter/scanner
The OBD2 system has 5 protocols, and they vary per car model. Below are the 5 different protocols, and which 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 10 and pin 2 provides the + signal.
SAE J1850 PWM Protocol, used by most cars and FORD.
This protocol must have pins 2,4,5,10 and 16. Pin 2 provides the + signal, while 10 the – signal.
ISO 9141-2, an older protocol found on European vehicles between 2000-2004.
KWP2000/ISO 14230-4, a very common protocol found in 2003 and up vehicles (mostly 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), which can be found on newer cars. The most modern protocol. Usually found on cars made after 2008.
This protocol must have pins 4,5,6 and 14. Pin 6 is CAN high, and pin 14 is CAN low.
For more reading on what the OBD2 pins mean and how the protocols and PIDs work you can check out the information rich wiki here. The PIDs will show you the general information that all OBD2 cars will show and how it works out the data and displays it.
By using the OBD2 pinout guide above, you can take away the guesswork and successfully 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 already OBD2 compliant prior to 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 as well that can help you out.
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 and clear faults. This scan tool here.
Pre 2006 cars and also newer cars – Full system scan tool that can do OBD2 and OBD cars. See this tool here.