Well, since I started this thread with a mercedes, I will finish it with a subaru. Same problem
I was very pleased when jimmy put a I love u note on my laptop tool box. the gateway was going ballistic. So I dumbed it down for jimmy, and I said do you have 58 to 62 ohms on pins can high and can low of dlc obd2 connector?
If no, you have a terminal resistance problem.
This also took a very sherlock holmes approach. All the wirings I could find had no indication of where gateway was, but it endend up being his install that was the prob. Most of these new units require a can line module.
For context Jimmy is our windsheild, remote starter and alarm installer, je is also good at modding big arse 4x4 we dont need, but at least it pays the bills so to speak./
So J9i was installing a remote start module in a 2018 subaru, and the car went crazy. He came to me and said, why is this new car acting crazy. I said check the can lines. easy check.
Lo and behold, his solder joints on the can lines where shoddy, and created a resistance the can lines could not tolerate. The baud rate on the scope was high, good thing we didnt smoke a peace pipe before this one.