OBD2 is a term that is used in the automotive industry to refer to the onboard diagnostics system. It’s an upgraded version of OBD1 and has more advanced features than its predecessor.
Your OBD2 system utilizes 1 of 5 protocols depending on the make and model year of your vehicle. In short, protocols are different types of communication between your vehicle and your diagnostic tool. Any OBD2 compliant vehicle can communicate with any of the 5 communication protocols, you just have to have the right OBDii connector.
What Is OBD2?
OBDII or OBD2, a short form for On-Board Diagnostics Two, is a system that diagnoses a vehicle’s system and displays fault codes along with other information such as transmission and system performance.
Since 1996, OBD2 systems have been mandatory in every car driving in the USA, however, some older models that date back to 1996 or older do not support OBD2.
An OBD2 scan tool connects into an OBD system and diagnoses any issues within the car‘s processes, from the engine control unit (ECU) and ABS to SAS, emergency brake system, emissions system, and more. If there is a malfunction there will be a diagnostic trouble code (DTC) displayed, such as a check engine light icon.
What are OBD2 Protocols?
Generally, an OBD2 system has 5 protocols. Different models utilize different OBDii protocols. Your car might have a type A protocol or a type B. Both of these have a physical difference in their ports (connectors).
Type A connectors possess 16 teeth placed in two opposite rows. Each row has 8 diagnostic connectors that sandwich a single “tongue”.
Type B connectors possess 16 teeth as well, however, they sandwich the tongue in two parts.
Does My Vehicle Contain OBD2?
Every car that has been sold in the US for the past 20+ years contains an OBD2 system. However, if you want to check if your car has it or not, you can easily do it yourself.
All you need to do is look for the white sticker that says OBD2 compliant under the hood.
An even better option is to look for an OBD2 port under the dashboard where an OBD2 scanner connects.
Where Is The Connector Located?
The OBD2 port is usually in the same place as the Hum System. As it helps the network communicate with your car directly.
You can find the connector in one of these places depending upon the car model:
- Under the glove department.
- Under the dashboard, right beneath the steering column.
- A couple of feet away from the car’s centerline.
You can also find the location of your car’s connector by going here and feeding the details.
Types Of OBD2 Protocols
There are 5 types of OBD2 protocols:
- SAE J1850 – Ford
- SAE J1850 PWM – General Motors
- ISO 9141-2 – Asian and European vehicles, as well as Chrysler
- ISO 14230 KWP2000 – Asian vehicles
- ISO 15765-4/SAE J2480 (CAN) – US vehicles made after 2003
- SAE J1850 VPW: This OBD2 protocol is used by Ford.
- SAE J1850 PWM: General Motors utilizes this protocol.
- ISO 9141-2: You will find this protocol on Asian, Chrysler, and European cars.
- ISO 14230 KWP2000: This protocol is found in Asian vehicles.
- ISO 15765-4/SAE J2480 (CAN): You’ll find this protocol in many new cars as it was invented for cars that were not subjected to OBD2 standards by law. Since it couldn’t satisfy the OBD2 requirements for U.S vehicles that came before 2003. You will find this protocol in many vehicles made after 2008.
Which OBD2 Protocol is Supported By My Vehicle?
For a protocol to be J1850 PWM, pin 2 and pin 10 must be there in the connector (the connector must have metallic contacts inside pins 2, 4, 5, 10, and 16.)
J1850 VPW must have pin 2 (the connector must have material contacts inside pins 2, 4, 5, and 16, but not 10.)
ISO9141 and 14230 (KWP2000) must have pin 7 while pin 15 is optional (the connector must have metallic contacts inside pins 4, 5, 7, 15, plus 16.)
ISO 15765 (CAN) should have both the pins, 6 and 14 (the connector must have material contacts inside pins 4, 5, 6, 14 and 16.)
The alignment and availability of pins in the connector will determine your car’s specific protocol.
What Does Each Pin Do?
Looking at the DLC pinout, you can determine which OBD2 protocol your vehicle model supports. This is important because not every protocol connects with the scan tool in the same way. This is due to different OBD2 protocols in different models of cars.
Look at the internal teeth on the serial bus and determine which pins are in use and which are empty.
There are 8 pins at the top row and 8 pins at the bottom row. Here’s the use of every pin:
Pins On The Top
- Pin 1: Used for OEM COMM.
- Pin 2: J1850 Bus+ is located on this pin.
- 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.
Pins At The Bottom
- 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: Pin responsible for powering the scan adapter.
Now that you know how many pins are there and what are individual pins for, you can look at the protocol in your car and determine the pinout of the OBD2 scanner that will fit.
The Bottom line
If your car is younger than 1996 then it will most likely have an OBD2 system. Still not sure? Then you may take your car to a professional.