w211 E500 No engine ECU communication

Hi Guys,

A friend of mine who bought my old w211 E500 has developed an issue where the car lost all communcation with the ME2.8 ecu and also the Fan is on high indicating it indeed lost communication with the ECU.
He had this issue before after he was in a small collision, the car worked fine after the accident though but after a few days of sitting it somehow lost connection with the ECU,
We couldnt work on the car for atleast a week and when we came back the car started right up and drove for months without any issue's.

The issue has now come back though and i cant seem to find where the problem is exactly.

First thing we did was swap his ECU into my car (also w211 E500).  the car wouldnt run on that ECU offcourse but it did start and the FAN was NOT on indicating the ECU itself looks to be fine.
When i swap my ECU into his car it still doesnt get recognized so its probably wiring or other modules acting up.
Das doesnt report anything unusual other then all other modules having the same fault: no communication with ME2.8.

Swapped out the front sam for a known working one i recently took out of my own car but same thing.
Checked CAN-C connector bus in driver side rocker panel but all seemed fine.

Going to check for schematics first, i do have a old DAS/c3 system but somehow cant open any other program anymore except Das so no way to really diagnose the wiring.
Does anyone here has a schematic for the ecu pins or any idea what to check next?

It seems obvious that you have a problem in the vehicle's wiring. Check the signal on both CAN lines at the engine control unit and don't rule out problems with terminal 87 from the engine control unit to the front SAM.

You should install WIS on your computer to have the necessary schematics.

Wis somehow stopped working a few weeks ago thats why i asked for a schematic but after i started this topic i did some maintenance on the old Dell laptop and Wis is working again so im happy with that.
Ive actually never had to measure or even work on can bus systems so i could measure but i have no idea what signals or voltages to expect so im doing some youtube en goodle study's as we speak to learn some basics.

Use this..

https://mhhauto.com/Thread-StarFinder-we...fline-2023

Completely forgot about this thread but here's an update.
I found the issue and made a temporary fix so he can atleast use the car.
Pin 3 on the Drivers Side Sam does not have 12v,  the thing is that its not 0v either, im measuring 5v and it looks to be regulated as well,  its not a random number close to 5v.
It has the same voltage as the 5v rail for the various sensors in the car.

After a few hours of not getting any further i just made a jumper wire with a relay to feed the 12V back into the fuse.
He has been driving it like this for weeks now but i think its time to dig into it again to fix it properly.

I did find some schematics in Das eventually but could only use them to find the issue i was missing 12v on pin 3 but didnt manage to find where pin3 goes or what powers it.