Evo OBD-II diagnostics utilize the ISO-9141 standard, a serial protocol distinct from RS-232 or USB. Direct connection isn’t possible. For those interested in experimenting with a direct connection, consider constructing a “Jeffrey Obdii” cable. This cable design, detailed at http://www.planetfall.com/~jeff/obdii/, employs opto-isolators and transistors for electrical translation. Despite referencing Volkswagen, the core principles apply to Evo vehicles.
Understanding Jeffrey OBDII and Software Compatibility
The Jeffrey OBDII cable provides the foundational physical layer translation. However, the OBD-II protocol’s software implementation requires careful consideration of baud-rate fluctuations and timing complexities. Freediag, an open-source Linux-based software available at http://freediag.sourceforge.net/, offers a potential solution for implementing the necessary protocol. Additionally, Malibu Jack’s Mitsulogger (http://www.aktivematrix.com) is reported to be compatible with this cable type.
Alternatives to Jeffrey OBDII: Roadman’s Cable
An alternative to the Jeffrey OBDII cable is Roadman’s cable, which incorporates a microcontroller to manage baud-rate and timing challenges. While simplifying certain aspects, this approach introduces a proprietary protocol requiring specific programming. Roadman’s software or freediag can be used with this cable.
Jeffrey OBDII vs. Tactrix Cables for Flashing
Neither Jeffrey OBDII nor Roadman’s cable is compatible with software designed for Tactrix cables. They lack a USB interface and cannot be utilized for flashing purposes. Replicating a Tactrix cable’s functionality at a lower cost is improbable due to its complexity.
Conclusion: Jeffrey OBDII for DIY Diagnostics
The Jeffrey OBDII cable presents a viable option for Evo owners seeking a hands-on approach to diagnostics. However, it’s essential to acknowledge the complexities of software implementation and protocol compatibility. While offering a deeper understanding of vehicle communication, this method requires technical proficiency and is best suited for those comfortable with electronics and software development. For flashing or simpler plug-and-play solutions, commercially available options like the Tactrix cable remain the preferred choice.
