Verify that the ground pin of your OBD2 interface/tool is tied to the exact same ground source as the ECU power supply ground.
Are you trying to (read/write) or troubleshoot a no-start ? bosch me20 pinout verified
Using this pinout data requires a careful, methodical approach. Here's a step-by-step guide to help you: Verify that the ground pin of your OBD2
Pin 6 (Outputs a ground signal to trigger the fuel pump relay). Step-by-Step Guide for Bench Setup and Flashing Here's a step-by-step guide to help you: Pin
To help with identification, all Bosch ECUs start with serial numbers like 028… or 026… . If you have a Bosch ECU in hand, you can use these numbers to search the official Bosch databases, which can help confirm the exact model.
For diagnostics and tuning, the communication lines are the most sought-after pins.