Mercedes-Benz Forum banner

It Just Keeps Getting Better... DTC 1904/1974/1978 After Battery Swap

1030 Views 8 Replies 2 Participants Last post by  Planethill
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 "why is that coming up now?"
Scans showed DTC 1904, 1974, and them and saw the car not in park.
I figured it's running so I cleared the faults and thought I would go for another drive, well no dice!
It will not go out of Park now and the dash is telling me not to change gears and drive to the shop haha...its in Park so I cannot go anywhere.
It seems to think I am in gear vs park.
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 up and running too... :(

So I assume I need a new ISM now or a reprogramming?
Anyone have an idea or experience with this?
1 - 5 of 9 Posts
Yeah I'm using a launch touch Pro scanner and while it can do a lot it definitely can't reset an ISM. I definitely need to try and find somebody with a star to see what they can figure out. I definitely need to try and find somebody with a star to see what they can figure out. I'm sitting in the car right now and my plan was to reverse what I did and see if it makes any difference by putting the old auxiliary battery back in. The car is in park but it thinks, via the ISM, that I am in gear so as soon as I open the door with the car running it tells me door open car in gear but it's in Park. Thanks for the reply!
  • Like
Reactions: 1
Whoa who whoa....they do surgery on rockets!? 😆
All jokes aside, I decided to go out and Tinker 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.

So then I decided to 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.

Building a STAR? Really?
See less See more
OK nice, I know there are loads on Ailbaba too.
I am a computer nerd and might have an old laptop with a serial port.
1 - 5 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.