Hi i have some weird issues with a mercedes s350 w222 2013
No communication with ECM
No cummunication with TCM in al the control modules .
First day we replace terminal 15 realy in the rear sam unit car started all fine after half hour all dead again check the relay terminal 15 all good checked all the fuse boxes realys and fuses all good
Anyone had this issue before ?

You might try posting in W222 forum, this is W221, earlier model than yours. In any case, what codes are being thrown? What does DAS/Xentry say?

Hi here is the codes using an autel maxysis

Are you able to connect directly to the engine and transmission modules with your scanner? If not, you need to start by checking for power at those modules. It is possible that you have CAN bus issues, but it looks more like power problems to me. Once you have established that everything is powered and communicating with the ECU and TCU, clear all codes and start fresh. If you still have a no start, start with the immobilizer and go from there.

That’s the problem we cannot get communication with ecm, we checked the all fuses, fuse boxes , relays in the car all fine. In the rear Sam unit we have an 15 amps fuse for rear Sam unit wich is dead no live no earth on it we open the rear Sam unit and check the board circuit is all fine !

Check power AT THE ECM CONNECTOR. Which circuit (fuse number) are you referring to in the rear SAM? Does the dash light up with key in position two, (or two clicks of start button without your foot on the brake if using keyless go)?

Fuse number 432 rear fuse box is the one that is no signal on it at all
this is what I get with ignition on

Also we checked pins that is giving live to the ecu and they all have live on so the ecu is getting power also we disconnected the gearbox ism module and tried to connect to the ecm with the diagnostic and no luck , we run a test plan with the Mercedes diagnostic and at the end of the test al the fuses that we been asked to check was ok also all the wires ok at the end of the test the result was REPLACE N127 Drive train control unit !

I was assuming no start, no crank, is that correct?

Yes no start no crank no gears any ideas what it could be ????

Well, N127 is a gateway module, so it being bad would certainly cause a lot of communication problems. Before you replace it, I would check that it has power and attempt to communicate with it. It is an easy module to get to and not overly expensive, so it would be relatively good news if it is faulty. At any rate, you have communication problems on multiple buses, so gateway modules, power/ground issues, and CAN terminal blocks would all be suspect. If you can communication with the EIS, check for fault codes on that module. It is another gateway and might give you some clues, especially with drive authorization.

The N127 has power on the pins wich the star diagnostic point to check so it only leaves me to replace it and see how it goes , no communication with EIS in all the control module that I can get connected and they control drive authorisation comes up as DRIVE AUTHORISATION OK!

Also anyone can help spreading this post around maybe we get someone that had a similar issue to come up with an idea I’m new to this forum and don’t know how to move this in the right place where more people can see it !
Thanks!

Hi bro. What happened about your car is there any result you get.let me know . Maybe i can help you.

Hello, any update on your repair? Please update the status. Thank you

hello did you come up with a solution to that car thanks

Hello, were you able to fix the issue on you car?