Regardless of which OBD2 protocol you currently have, one of the best things about OBD2 technology is that it is standardized. For example, it doesn’t matter which car or model you have. If you bought it after 1996, you can use any OBD2 scanner tool with it and enjoy all that OBD2 technology has to offer.
However, despite the standardization, there are slight differences among OBD2 protocols in cars from different manufacturers. This doesn’t mean that you’ll require some special scanner tool specifically for your OBD2 Protocol. Your usual scanner will work just fine.
Nevertheless, you still need to know what these protocols are, and which one your vehicle supports.
- 1 What is OBD2 Protocol?
- 2 Types of Protocols
- 3 What are the Ways to Check My OBD2 Protocol?
- 4 Which OBD2 Protocol is Supported By My Vehicle: The Examination of the OBD2 Connector Pins
- 5 OBD2 Connector Types
- 6 OBD2 Connector Pins Interpretation
- 7 The Bottom Line
What is OBD2 Protocol?
To put it in simple words, the protocols are the different ways your vehicle’s OBD2 system communicates with the OBD2 scanner tool and produces the Diagnostic Trouble Codes (DTC). So, essentially, they all say the same thing, but they say it in their own way. Moreover, these differences arise because different car manufacturers prefer different protocols in their vehicles.
Although, you can still plug in any OBD2 scanner without worrying about the OBD protocol. However, the only difference will be which pins the scanner tool uses.
Types of Protocols
Different protocols use the 16-pin connector differently. As a result, there are five most commonly used pin combinations. Your car will most likely be using one from the OBD2 Protocol list below.
Let’s discuss each of them in a little bit of detail.
1. SAE J1850 PWM (Pulse Width Modulation)
If you own a Ford, it will most probably be using this protocol in its OBD2 system. This OBDII protocol has a signal rate of 41.6 kbps. Moreover, it has a maximum signal voltage of 5V and a minimum of 0V.
Furthermore, Pin 2 is for the Bus Positive Line, and Pin 10 is for Bus Negative Line. Also, the message length in this protocol is limited to 12 bytes. This protocol uses an arbitration scheme known as Carrier Sense Multiple Access (CSMA).
2. SAE J1850 VPW (Variable Pulse Width)
Normally, General Motors’ vehicles use this protocol. It has a signal rate of 10.4 kbps. Also, it has a maximum signal voltage of +7V and the minimum signal voltage of 0V, along with a decision signal voltage of +3.5V.
Similar to SAE J1850 PWM, this protocol also uses Pin 2 for Bus Positive Line but not Pin 10. Moreover, it also uses CSMA and has a message length of 12 bytes.
3. ISO 14230 KWP2000 (Keyword Protocol 2000)
Chrysler and many of the European and Asian vehicles include this protocol. This OBD2 protocol also has a signal rate of 1.2 to 10.4 kbps. Additionally, it has a maximum signal voltage of +12V and minimum of 0V.
Moreover, Pin 7 is for K-Line, and Pin 15 can be for L-Line. This protocol has a similar physical layer as ISO 9141-2. Also, the message length can go up to 255 bytes.
4. ISO 9141-2
Similar to ISO 14230 KWP2000, this protocol is also usually found in Chrysler, European and Asian cars. Moreover, it also has the same signal rate and the same maximum and minimum signal voltage.
Furthermore, this protocol uses UART (Universal Asynchronous Receiver-Transmitter) Signaling. Also, the maximum message length is 260 bytes.
5. ISO 15765 CAN (Controller Area Network)
In the US, all vehicles sold after 2008 have been authorized to use this protocol. Although, some European vehicles sold after 2003 also use this protocol. This is the most recent protocol with a signal rate of 1 Mbps.
This protocol uses Pin 6 for CAN High and Pin 14 for CAN Low. Moreover, this OBD2 protocol has four further variants which are sometimes confused as separate protocols.
All protocols use the pins differently, except for two pins which are same for all. Pin 4 is for the battery ground, and Pin 16 is for battery positive in all five protocols.
What are the Ways to Check My OBD2 Protocol?
There is a very simple method to check which OBD2 protocol your car is using. All you have to do is study the OBD2 port or Diagnostic Link Connector (DLC). If you take a closer look at the OBD2 port, you’ll notice that it’s a 2×8, 16-pin, D-shaped connector.
Therefore, you need to see which pins this port is using. Consequently, the pins that are in use will have some metallic contacts inside it. Moreover, after noting this down, you can cross check with the different protocol’s pins and determine which protocol you have.
So, here’s how you can identify all the protocols from the pinouts:
- SAE J1850 PWM: The DLC must have Pin 2 and Pin 10. Also, there must be metallic contacts inside Pins 2, 4, 5, 10, and 16.
- SAE J1850 VPW: The DLC must have Pin 2. Additionally, there must be metallic contacts inside Pins 2, 4, 5, and 16.
- ISO 14230 KWP2000 or ISO 9141-2: The DLC must have Pin 7, and Pin 15 is optional. Moreover, there must be metallic contacts inside Pins 4, 5, 7, 15, and 16.
- ISO 15765 CAN: The DLC must have Pin 6 and Pin 14. Also, there must be metallic contacts inside Pins 4, 5, 6, 14, and 16.
Besides that, as mentioned previously, all car manufacturers use their own protocol so you can determine your OBD2 protocol by checking which one your vehicle uses. But a better way to check is to look at the pinout. Moreover, you can do this easily by comparing your car’s OBD2 port and the pinout table we’ve given below.
Which OBD2 Protocol is Supported By My Vehicle: The Examination of the OBD2 Connector Pins
As you must have realized by now, the protocol is all about the connector’s pinout. So, we’ll tell you some more about the connector types and how to interpret the pins.
OBD2 Connector Types
There are two main connector types:
- Type A
- Type B
Both of these are the usual 2×8, 16-pin, D-shaped, female connector. However, there is a small difference. Type A connectors have one groove running between the two rows of pins.
Whereas, Type B connectors have a groove with a gap in the middle. Moreover, vehicles that require 12V supply voltage use Type A connectors. While vehicles that require 24V supply voltage use Type B connectors.
OBD2 Connector Pins Interpretation
Here is a standard pinout of an OBD2 connector:
- Pin 1: Manufacturer Discretion
- Pin 2: Bus Positive Line of SAE J1850 PWM and VPW
- Pin 3: Manufacturer Discretion
- Pin 4: Chassis Ground
- Pin 5: Signal Ground
- Pin 6: CAN-High
- Pin 7: K-Line
- Pin 8: Manufacturer Discretion
- Pin 9: Manufacturer Discretion
- Pin 10: Bus Negative Line of SAE J1850 PWM Only
- Pin 11: Manufacturer Discretion
- Pin 12: Manufacturer Discretion
- Pin 13: Manufacturer Discretion
- Pin 14: CAN-Low
- Pin 15: L-Line
- Pin 16: Battery Voltage
Accordingly, now that you know how to interpret the pins, all that is left to do is check under your car. Furthermore, you can do this easily by referring to the following table to check your OBDII protocol.
OBDII Protocols Table
|Protocol||Pin 2||Pin 6||Pin 7||Pin 7||Pin 10||Pin 14||Pin 15|
|SAE J1850 PWM||Present||-||-||Present||-||-||-|
|SAE J1850 VPW||Present||-||-||-||-||-||-|
|ISO 14230 KWP2000 or ISO 9141-2||-||-||Present||-||-||Optional||-|
|ISO 15765 CAN||-||Present||-||-||Present||-||-|
The Bottom Line
In case, you still can’t figure out your OBD protocol, you can just do a quick internet search of OBD2 protocols by vehicle make and model or OBD2 protocol by the manufacturer of your vehicle.
Moreover, just to reiterate, having a different OBD2 protocol does not affect which scanner tool you use. Although, a general idea of your OBD2 protocol by the manufacturer can help you use your OBD2 technology better.