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

1072 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?
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Are you using a generic scan tool? If so it most likely will not clear all Mercedes specific codes/faults. Before throwing parts at it, I would find someone with a Mercedes Star computer to do a real reset and scan of the module(s). Changing batteries, low voltage, etc can cause all sorts of wonky behavior.
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Have you tried just exercising it? Shifting from Park to Drive and back a dozen times, etc? Maybe it just needs to get it's bearings to normalize, like windows and sunroofs. :D

If you work on your Mercedes a lot, look into building an SDS box yourself. It isn't rocket surgery, and it's a lifesaver in my opinion!
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Building a STAR? Really?
Yup! You just need an old laptop (must have a 9-pin serial port), a Chinese multiplexer and cables (kits are everywhere), and the Star software which can be found at MHH Auto and others. If building a computer from scratch is too daunting, you can even buy a hard drive pre-loaded with everything, although it's more of a mystery what you are getting and some things might be locked, etc. Or, if you have a lot of extra cash, there are people doing all of the above for you, selling a turn key system.
Me too! It's not hard at all. And don't believe the hype that it must be a "Dell XXX" whatever. That is only if using a pre-imaged hard drive and you want it to be plug-n-play. Drivers, etc.
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