Activate Benz COTEL in basic module with MB STAR diagnosis

One of obdii365 customers has got the MB STAR diagnostic tool but he did not know how to activate the COTEL in base module. Our engineer worked out the solution and displayed the step-by-step instructions.

What’s COTEL interface?

MB uses a proprietary protocol on their trucks, so you cannot connect directly to the vehicle CAN bus. With most trucks from BENZ, you have the option of installing/enabling the COTEL interface, which is the implementation of FMS. On relatively recent Actros trucks, the COTEL interface is implemented in the main module in the passenger footwell but in nearly all cases it has to be activated by the dealership, AFAIK because it stores an error state when there is no device connected (i.e.: no ACKs).

You can get the CAN signals from the truck at Base Module (main fusebox on the right side of the cab) at connector X5. But for any messages to come out from there, COTEL interface must be activated by MB dealer with Star Diagnosis computer. You will also be able to get from them all pins and plugs needed to plug the connector into base module. Activation is a 5 minute job with the star diagnosis system.

Tool needed:
MB STAR diagnostic system: MB SD Connect Compact 4, Super MB STAR C3, best quality MB STAR C3 pro multiplexer

NOTE: Best price MB STAR C3 multiplexer cannot work on Benz truck model.


1. Run Self-test

Well install Benz MB STAR diagnostic software XENTRY/DAS
Connect MB STAR diagnostic system with vehicle
Start XENTRY>> Benz>>Trucks
Start diagnosis
Start Quick test, press F2 to confirm
Confirm displayed VIN and mileage
Run Quick Test

2. Select “Base module (BM)” menu item

“Control unit list” ->>“Register new control unit” -> >“COM communication interface”
Set COM to “AVAILABLE” and confirm
Select “Register new control unit”>> “COM communication interface”
Select “Telematics” option and set Telematics to “AVAILABLE” and confirm

3. Activate/Inactivate the CoTel interface

Select “Base module (BM)” menu item
Select “Control unit adaptations” menu item
Select “Vehicle equipment”
Select “Vehicle configuration”
The CoTel interface menu item is shown. You can change the status to “YES” (activate) or “NO” (inactivate)
The COTEL interface in basic module has been activated.
Go back and exit the MB STAR software
Disconnect STAR diagnosis system.