Reading the Mercedes EDC17CP57 with KTAG 7.020 using the GPT cable is a reliable method for tuners. The key to success is accurate identification of the GPT pads on the PCB and ensuring a stable power supply throughout the reading process. Always keep a backup of the original file on multiple storage devices.
Check your 12V power supply. Ktag requires a constant voltage; a weak laptop USB port is not enough to power the ECU. How to read Mercedes EDC17CP57 with Ktag 7.020 GPT cable