OBD-II to DB9 Cable

Once you've hacked everything, why not go out in the garage and hack your car? This cable allows you to access the pins on your car's OBDII connector. It has an OBDII connector on one end and a DB9 female serial connector on the other. The overall length of the cable is 5'.

**Note: **This cable is not meant to be plugged directly into a computer's serial port. It is meant to plug into some sort of hardware interface.

Here is the basic pinout (OBDII > DB9 Female)

Pin Description OBDII DB9
J1850 BUS+ 2 7
Chassis Ground 4 2
Signal Ground 5 1
CAN High J-2284 6 3
ISO 9141-2 K Line 7 4
J1850 BUS- 10 6
CAN Low J-2284 14 5
ISO 9141-2 L Line 15 8
Battery Power 16 9

OBD-II to DB9 Cable Product Help and Resources

Getting Started with OBD-II

October 8, 2015



Looking for answers to technical questions?






  • Please consider changing the product name to "OBDII to DB9 Cable". You have an OBDII connector on one end, and a DB9 connector on the other end. There is no such thing as a "serial connector", only serial protocols. While there are serial protocols involved, they are not the RS-232 serial protocols people expect when they see a DB9 connector. Using the term "serial" to describe the product is likely to lead to more confusion.

    • Seconded. If its got a DB9 and you call it a serial connector, people will naturally be inclined to think its RS-232 serial. Even when you say "its not meant to be plugged into a computer serial port" that almost seems too soft. "It can't be used with a computer serial port" is a bit more to the point, I feel like. Hopefully this doesn't just seem nitpicky, but its important to be clear on this stuff.

    • Adding yet another nitpick - technically that connector is a DE-9F, not a DB-9. The "B" shell is for the 25-pin-size connectors.

  • The pinout can't be right....Pins 1 and 2 are the J2850 BUS+, and also signal and chassis ground in the current table. The J2850 BUS+ signal should be on pin 7 of the DB9 by process of elimination...I don't have a cable to verify this, though.

  • I want to read my car's speed while in motion. Can I create some type of setup with this cable to send the info to an arduino?

    Or do I need extra hardware such as the "Car Diagnostics Kit Retail" sold here on SparkFun?

    Thanks in advance!

    P.S. Someone please reply lol

    • The cable simply allows you to interface with a DB9 port on your car. You'd still need either a CAN IC or OBD-II IC to actually communicate with the vehicle. Check the car diagnostics kit to get a bit more info about starting on that.

  • how much current can be pulled from the 12V?


  • Buyer BEWARE:






    • Thanks for the information and sorry for the problems.

      If anyone finds that these don't fit well, please don't force them, and contact our Customer Service department; we'll be happy to arrange a return if they don't work for your application.



  • Why is there a signal ground? It looks like all those signals are differential...

  • This is sadly not a "standard" ODB-II to CAN DB9 cable. For example, it WILL NOT WORK with the AVR-CAN Sparkfun also sells. (Although I have not tried it, it's obvious based on the pinout here and the AVR-CAN schematic.)
    If you search Google and Google Images for "CAN DB9", it's pretty obvious that lots of things use the AVR-CAN-style pinout, and not the one used by this cable. I'm not sure if there's an actual standard for this, though.
    At any rate, a note that this won't work with the AVR-CAN should be added.

    • It's not a CAN cable, it's an OBD-II cable. OBD-II contains CAN but it also contains several other protocols. The pinout of this cable matches all the other OBD-II to DB-9 cables I have seen online.

  • http://www.gridconnect.com/canusblight.html
    I recommend gridconnect.com for any CAN to USB or serial port needs. I've worked with their USB-CAN adapters and software and it is the best-performing for the price. The API is relatively simple and for $259 you can get drivers and source code (in C) for windows. The link listed above is a simple serial-can bridge to work with teraterm or hyperterminal


      I paid for the SAE's OBD-II (J1979) standards document, but for most of the more common PIDs you can find the information you want online. If you want manufacturer specific PIDs (like Ford's internal codes for the RAP module, etc.) be prepared to have some difficulties. The individual extentions to the standards are extremely proprietary and licensing them for use can cost as much as $10k-20k.

  • Everyone's points are noted.
    I fixed the pinout, it was incorrect.

  • Don't you mean J1850, instead of J2850? Is this for connecting to the Chinese ELM327 clone boxen?

  • my guess; we can't connect this cable to computers serial port, is it true?

Customer Reviews

3.7 out of 5

Based on 3 ratings:

Currently viewing all customer reviews.


This cable makes much easier to connect to OBD-connector and gives any hacks professional look. Enough long, in case connector is in some lousy place. Can't really say anything more about it

Works well

The cable transports the power and CAN bus signals without a hitch. I haven't needed the other pins yet. As another reviewer noted, it looks good -- much better than any hand-rolled solution I've seen.

I had some concern when I received this cable due to the OBD-II end being rubbery instead of solid plastic, but that hasn't proven to be a problem with the two vehicles on which I've used it.

I've run the cable under the driver-side floor mat and over to the center console (keeping it out of the way of the driver's feet) and the cable was no worse for wear after a multi-state trip, so it seems to be well made.


Need full 16 pins so I can get iso, vpw, pwm and can

Need a db25 to carry 16 wires