Replacing an ECM in a 2016 Subaru Crosstrek can present unexpected challenges, particularly when it comes to VIN writing. Many technicians rely on aftermarket scan tools like the Verus, but the question remains: can it rewrite the VIN on a replacement ECM? This article explores this issue and provides insights gained from a real-world ECM replacement scenario.
VIN Writing and J2534 Compatibility
Aftermarket scan tools often utilize a J2534 pass-thru device for programming and diagnostics. While J2534 devices are versatile, their compatibility with VIN writing on Subaru ECMs is often limited. In our experience with the 2016 Crosstrek, neither the Snap-on Verus nor a newer Launch scan tool could perform this function. Identifix, a trusted source for automotive repair information, confirmed that the Verus, even with a Cardaq 3 Plus and J2534 interface, lacks the capability to write the VIN to this specific Subaru ECM. They indicated that the difference in hardware between the J2534 and Subaru’s proprietary hardware is the limiting factor. Altel scan tools are rumored to have this capability, but we haven’t been able to confirm this.
Dealer Intervention and the Green Check Connector
Due to the J2534 limitation, Identifix advised taking the vehicle to a Subaru dealership for VIN writing. This raises another question: does the 2016 Crosstrek have a “green check connector” that needs to be connected for this procedure? Some Subaru models require this connector for certain programming functions. Despite thorough searching under the dash, under the carpet, and near the ECU, we couldn’t locate it on this Crosstrek. Its existence and necessity for this specific model year remain unclear.
Lessons Learned from a Crosstrek ECM Replacement
This ECM replacement presented several challenges beyond VIN writing:
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Pre-programmed ECM: Even though the replacement ECM came pre-programmed, VIN writing was still required. Connecting to the vehicle with a J2534 device and the latest Subaru reprogramming CD confirmed the existing calibration was current.
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Subaru Reprogramming Resources: Reprogramming or “fix type/TSB type” reprogramming requires a specific $75 disc ordered from Subaru’s technical information provider. Obtaining this disc requires persistence due to slow response times. The disc, however, does not have an expiration date and can be used on multiple vehicles.
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Subaru Flashwrite Software: This software requires a user-defined username and password upon initial setup. Accessing the correct calibration involves navigating through year, make, and model. The “decryption keyword” provided in the calibration information is crucial for the programming process.
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Lack of Crank/Cam Relearn Provision: The 2016 Crosstrek ECM doesn’t have a built-in crank/cam relearn procedure. If learned values deviate significantly from their normal range, ECM replacement becomes necessary, even if the root cause of the initial problem is resolved. Otherwise, persistent P0018, P0016, or similar codes will continue to trigger. These codes force the cam timing to base timing, impacting performance until cleared.
Conclusion
While the Verus is a powerful scan tool, it’s not equipped to rewrite the VIN on a 2016 Subaru Crosstrek ECM. This limitation necessitates a trip to the dealership or potentially using specialized tools like the Autel. This experience highlights the importance of researching specific vehicle requirements and tool capabilities before undertaking complex procedures like ECM replacement. The lack of a crank/cam relearn procedure further emphasizes the need for accurate diagnosis and repair to prevent unnecessary ECM replacements.
