If you’re working with Bosch ME2.1 ECUs, you may have noticed that the KT200 software officially supports writing only via OBD. However, one user has successfully managed to write to the ME2.1 ECU in bench mode using the KT200 and shared his experience. Here’s a breakdown of how it was done — this method might save you time and open up new options for similar ECUs and tools.
Setup Summary:
ECU: Bosch ME2.1 (commonly used in Mercedes W201/W202)
Tool: KT200 ECU Programmer
Mode: Bench Mode using ME2.1 OBD driver
Connection Type: Manual bench wiring using croco clamps and standard 12V cables
Bench Wiring Details:
The key discovery is that the OBD communication pins are directly connected to the ECU, allowing bench writing using the same protocol.
Pin Connections:
K-Line → Pin C39
+12V (shared) → Pins A2 and B4
Ground → Pin A3
+12V (separate) → Pin B3
Tip: Use a separate 12V line for B3 to control the “dashboard” signal (ignition simulation).
Voltage used: ~15V on 12V lines
Bridging: Use croco clamps for temporary connection between A2 and B4.
Step-by-Step Procedure:
Prepare the Bench Setup
Connect all pins as described.
Make sure the 12V line to A2 and B4 is disconnected at first.
Start the Writing Process
In the KT200 software, click “Write” and confirm both dialog messages.
Activate the Dashboard
Turn on your power switch to supply 12V only to B3 (ignition signal).
Bridge Power Pins
After 2–3 seconds, connect your 12V power to the bridge between A2 and B4.
Writing Begins
Wait 5–10 seconds. The writing process should now start automatically.
Finalizing
When prompted to “turn off dashboard”:
Disconnect the 12V from the A2/B4 bridge first.
Then switch off the power to B3.
Let the process complete and confirm with “OK”.
Notes & Tips:
This process mimics the OBD signal structure over a bench setup.
It may work with other tools that allow manual signal and ignition simulation.
Be cautious with power supply voltages. The user reported ~15V working reliably.
Final Thoughts
This clever workaround proves that with some experimentation and understanding of ECU pinouts, you can bypass limitations in software and hardware. The ECUHELP KT200 might not officially support ME2.1 bench writing, but it works with the right approach.