Are you a BMW enthusiast looking to delve into DIY diagnostics and coding without breaking the bank? The Blue Vag Kkl Obd2 cable, often used for VAG (Volkswagen Audi Group) vehicles, can be easily modified to work with many older BMW models. This guide, inspired by the resourceful members of bmwecu.org, will walk you through the simple modifications needed to get your VAG KKL cable BMW-ready. We’ll focus on making this accessible for users who want to use software like INPA, easyDIS, and NCS Expert on their BMW, specifically models from approximately 1999 to 2007, including the popular E46 330Ci test vehicle.
Understanding the Blue VAG KKL OBD2 Cable
The VAG KKL cable is a budget-friendly diagnostic tool primarily designed for Volkswagen, Audi, Skoda, and SEAT vehicles. Its affordability and widespread availability on platforms like eBay make it an attractive option for DIY car enthusiasts. These cables are inexpensive because they are mass-produced for a large market. However, straight out of the box, they aren’t fully compatible with BMWs due to differences in the diagnostic communication protocols and pin configurations. This is where our simple modification comes in.
Essential Modifications for BMW Compatibility
To adapt your blue VAG KKL OBD2 cable for BMW diagnostics, two key modifications are required. These modifications ensure the cable correctly interfaces with BMW’s K-Line communication system and properly signals the vehicle’s ignition status.
OBDII Connector Modification: Bridging Pins 7 and 8
BMW diagnostic systems utilizing the K-Line rely on pins 7 and 8 of the OBDII connector. By default, the VAG KKL cable may not have these pins correctly configured for BMW’s specific implementation. Bridging or shorting pins 7 and 8 together on the OBDII connector is a crucial step. This ensures the K-Line communication is properly established for diagnostic software to communicate with your BMW’s modules.
Image: Backside of the OBDII connector of a blue VAG KKL cable showing pins 7 and 8 before the modification to bridge them for BMW compatibility.
To perform this modification, carefully solder a small wire or solder bridge to connect pins 7 and 8 on the backside of the OBDII connector of your VAG KKL cable.
Image: Modified OBDII connector of the blue VAG KKL cable with pins 7 and 8 bridged using solder, making it suitable for BMW diagnostics.
FTDI Chip Modification: Connecting Pins 17, 18, and 20
The VAG KKL cable uses an FTDI FT232BL chip to handle USB to serial conversion. For BMW diagnostics, specifically to correctly detect ignition status, pins 17 (GND), 18 (RI – Ring Indicator), and 20 (DSR – Data Set Ready) on the FTDI FT232BL chip need to be connected. In BMW systems, pin 1 of the OBDII port is often used for ignition detection (+12V). By shorting pins 17, 18, and 20 on the FTDI chip, we simulate this +12V signal via the USB connection, tricking the diagnostic software into recognizing that the ignition is on. This is essential for software like INPA and easyDIS to function correctly and display the ignition status as black circles in INPA, or simply acknowledge ignition in easyDIS.
Image: Pinout diagram of the FTDI FT232BL chip, highlighting pins 17, 18, and 20 which need to be connected for BMW diagnostic cable modification.
Locate the FTDI FT232BL chip inside your VAG KKL cable. Solder a small jumper wire to connect pins 17, 18, and 20 together. Pin 17 is ground, and by connecting 18 and 20 to ground, you are effectively sending the necessary signal.
Image: The FT232BL chip on the VAG KKL cable PCB before any modification, showing the pins prior to soldering.
Image: The FT232BL chip after modification with pins 17, 18, and 20 jumpered together using solder, completing the ignition detection modification.
Software and Testing Your Modified Cable
Once you have completed both modifications, your blue VAG KKL OBD2 cable should be ready for use with BMW diagnostic software. Popular compatible software options include:
- INPA: A dealer-level diagnostic software for BMW, offering comprehensive diagnostics and module programming capabilities.
- easyDIS (Diagnostic Information System): An older BMW diagnostic system, still useful for many older models.
- NCS Expert: Used for BMW coding and module customization.
After modification, connect your cable to your BMW and your computer. Launch your chosen diagnostic software. You should now be able to establish a connection with your BMW. Verify the ignition status is correctly detected in your software (e.g., black circles in INPA). You should also be able to read modules and perform basic diagnostic functions. While coding with NCS Expert is possible, proceed with caution if you are new to BMW coding.
Image: The completed modified blue VAG KKL OBD2 to USB cable, ready for use with BMW diagnostic software after the pin modifications.
Conclusion
With these simple soldering modifications, your inexpensive blue VAG KKL OBD2 cable becomes a valuable tool for BMW diagnostics and coding. This DIY project is a cost-effective way to access powerful diagnostic capabilities for your BMW. Remember, soldering requires basic skills and caution. If you’re uncomfortable with soldering, seek assistance from someone experienced. Enjoy exploring the diagnostics and capabilities of your BMW with your newly modified cable!
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