So I worked on my 2006 ML350 today, managed to get all the wheel speed sensors done and took it for a drive, no issues and no sudden weird braking moments that scared the crap outta me months ago and I stopped driving it.
All was well minus getting codes for low voltage due to the aux battery being dead.
I had a new one but just hadn't got around to changing it so I decided while i was at it I would do that too.
I removed the main battery and then the dead aux battery and put the new one and replaced the main battery.
Started up the car and ran my scanner again to make sure all those random low voltage codes were gone and sure enough they were, awesome however I noticed a new code, ISM.
I thought WTF why is that coming up now?
Scans showed DTC 1904, 1974, and 1978...read them and saw the car not in park.
I thought huh, its running so I cleared and and thought I would go for another drive, well it will not go out of Park now and the dash is telling me not to change gears and drive to the shop LMAO...its in Park so I cannot go anywhere.
How in the hell could the ISM get fried just changing the battery out!?
I cannot understand how these engineers got their degrees devising such moronic failures from such simple tasks.

I was so happy to get the ML running as my bloody 2013 Ford Flex just got coolant leak which might be the water pump...the water pump some other moronic engineers thought would be a great idea to put it INTERNALLY in the engine and run off the timing chain!?
Yeah but they put 2 o rings on it so if one fails it leaks fluid out until that clogs and the second one fails and leaks coolant into the engine and ruins it.

So I assume I need a new ISM now or a reprogramming?

 

It is not neccessarily needs replacing. I had it a few times on my car. The ISM just needed re-learning. There were voltage problems with batteries as well. Re-learing is performed with the star diagnosis (merc scanner)

 

Mmm OK, my scanner can't do that unfortunately.



I will have to see if anyone locally has STAR to see if the issue can be fixed.

 

Tinkered with the Mercedes again this morn.
I decided first to remove the negative from the main battery and had no change then I decided to remove the main battery and then the new auxiliary battery that I put in and put the old auxiliary battery back in, it still made no difference.

Defeated I put everything back together again...put the new auxiliary battery back into the car and the main battery back.
I connected everything up got in the car started it up and sure enough it goes into drive and reverse now took it for a test drive nothing wrong with it!?
I scanned the car, cleared the ISM fault, and re-scanned and it now says it's okay and operational so I don't know if it's some weird order of connecting the batteries or what that I did but it seems to be fixed.
Bloody MB!!
Replaced all 4 wheel speed sensors but I need to do the bearings as I am still throwing a code for the rear right, telling me to check the bearing.

 

That is good news. the problem solved itself!
Mercs are loaded with electronics. When everything works ok, its a pleasure to drive, but when something goes wrong in it, they're complete nightmare. I guess you got lucky this time

 

Ha I hope so!