I believe this event was
triggered by low voltage,
not failed security check

So restoring power and clearing fault should restore function.

 

In theory, delete the code, shut the car off. Wait until computers are sleep, and restart.

However, from what I have read, it will sound familiar to you: the low voltage can corrupt an EEPROM in the ISM, or the DSM. These modules are in read-write mode at all times to update counters. If the code is corrupted, it needs to be reprogrammed (overwrite the EEPROM with a new/fixed image). What is the first requirement for MB coding -> CONNECT to the CHARGER, DO NOT ATTEMPT coding on battery voltage ALONE


If the scanner is bi-directional, perhaps it can go into calibration mode and attempt to recalibrate. Assuming that is the problem, not sure if BenzNinja does this kind of work, or mail-in service. MB likely will replace the corrupted part.

SUMMARY: Again, another example of why we should not let our batteries run LOW. Once we know/suspect they are low, we need to charge them w/o even attempting to turn the key ON. Jumping is OUT of the question.These are computers on wheels.

UPDATE/EDIT: @CaliBenzDriver , what is your opinion about a solderless board was triggered with the low voltage+jump -> EIS, the miniboard the shifter attaches to, or the ISM (I hope we are not in this territory).

 

I'm not saying that some problem which has arisen over the years can't crop up that will make jumping the car dicey, but the car is obviously designed to be jumped if necessary. It even has jumping points under the hood so you can do it conveniently without removing the battery cover. I myself have jumped my car a few times when in a pinch.

Maybe you have a crappy ground somewhere that sent a voltage spike somewhere where it shouldn't have? This wouldn't happen when the car was new, but could happen over time... But this obviously isn't supposed to happen and won't happen to everyone regardless of age of the car. And if it does happen, it won't happen the same way...

Just my thoughts...

 

I wonder what the WIS says about this situation... A permanent vs a temporary limp mode...

 

I do not have any issues with my electricals, nor I had in the past. But I have seen several damaged components due to jumping vehicles in general, but on MB I have seen the most expensive ones.

If you know, and I mean mastered the topic, how to jump a car of any voltage, any brand please go ahead. For the general public, and for those still inexperienced in the topic my advice is to avoid jumping these vehicles. Better safe than sorry and $4K hole in the pocket. Just because the car has posts, which are, in my mind, convenience access points and not jumping points it does not mean you should jump the car.

My 2c

 

you're right JC, everything is possible given enough marginal conditions are present. We've sen goofy stuff happen with modules corrupting their coding. "No jump policy" is for educated ppl. The "convenient jump points" is for tow-truck road side operators. It also help keep battery sensor in the loop instead of bypassed during jump.

We should consider checking these systems for functionality.

Right now something's got this vehicle stuck in Park.

Lets see how solderless SCM report "PRND" actuation.
At this stage... we assume chassis has been rebooted and faults cleared already.

 

I see jump points like a "rat trap loaded with cheese" - Actually a perfect connection for smart CTEK, to prevent ever jumping!

> No jumping policy...
-- Don't let the vampire modules drain down
-- CTEK float the battery
-- or disconnect batts if over 2 weeks without use.


> DISABLE KILLERS...
-- The battery vampires are CAN-B sleepless modules.
-- No1 of wich is KEYLESS-GO as worst offender.

Oxidized solderless pins with variable voltage drive this KeyG gem purposely crazy.
No way Mercedes don't know... what's ruining basic reliability brings in riches

- (No solderless
+ No voltage swing)
= GREAT MERCEDES!

 

KeylessGo is the cheese/peanut butter of this trap. With KeylessGo, the system is always partially awake, and the connection to the post can drive a voltage spike through the circuit. I recall you once mentioned that some capacitors are low rated <20V, so anything is possible when the jumper doubts/misses and triggers a spike train through the awaken circuit.

If we visit MHH auto we will find a few instances of corrupted modules due to low voltages

 

Ah, I didn't mean you in particular, I meant the impersonal "you" regarding whoever has had issues with their car after jumping it...

I agree that jumping should be avoided, but Mercedes have also been jumped however many times in history without issue (even if sometimes with issue), so the fact that the car was jumped does not mean that the problem definitely stems from being jumped and not something due to the configuration of the car post-jump, or pre-jump low voltage...

By the way, the manual lists the jump starting procedure using the jumping points (for my car, it's on page 262).

 

What's the quickest way to get this car back on the road? Dealership quoted 1.6k for new ISM, is there anyone I can ship this module to, to get it re programmed or whatever it needs? I double checked the batteries and the AUX battery does actually charge while car is on. It is around 13.2v while engine is running while the Main is at 14.6. I don't think the module is bricked or anything because the scanner reads it and the permanent limp mode you guys seen above in the live data stream is only after I try shifting, when the code is cleared there is no perm limp mode.

I would appreciate your guys feedback on this. Thanks

 

You have tried a few helpful things.
By looking at this again: it may be time to call replacement


not first picnic: 11 round trips into safe mode


permanent it may well be...

these ISM modules are purpose built to get where you're at: dry gear assembly with solderless connections.

Have a look inside...here


dry gear assembly work

 

The permanent limp mode is only there when the code pops back up, when the code clears, it goes away. Is it possible it just needs a teach-in or re-initialization and not a replacement? And if I do need a replacement, is the dealer the only option?

 

https://www.upfix.com/product/merced...odule-repairs/ Can me shipping it out to these people fix my problem?

 

Well that is very encouraging: it's says "permanent" but that's not hard-set.

Let me see what fault code that is ...

P179A77 :
"The Redundancy System for DIRECT SELECT Was Activated The Commanded Position Cannot Be Reached."

P179D00 :
"The Redundancy System for DIRECT SELECT Was Activated".

That does seem like ISM can't shift PRND well ...

ARE YOU PARKED UP ON A HILL (slope driveway!) or flat by any chance ???
Much harder to shift out of Park.


These ISM are legendary for being "dealer items only".
They are security parts that do require Xentry coding.

 

 

There seems to be known issues with P179A77. For example, here is a link where people exchanging files to repair the DSM/ISM https://*******.com/Thread-DSM-Fix-error-P179A77



If you read the thread, you can see that MBENZTECH helped someone there. Here I am assuming that MBENZTECH in that forum is the same @MBENZTECH in this forum. If I am not mistaken, he owns Renn Motors LLC in Houston, TX. Perhaps worth contacting him either via this forum, or calling the shop directly ( https://g.co/kgs/vyqtBj2)

 

I am parked flat

 

you see how... not reaching position sends it into lock up mode.
That's the core issue.

If you park on a slope driveway... the current surge necessary to shift wasted the poor connections. This unit can be refurbed to then be reliable without causing CAN-C busy traffic.

 

Should I send my ISM to the company called Upfix? They do ISM repairs for my car. Is this a good alternative to dealer?

https://www.upfix.com/product/merced...odule-repairs/

 

Thank you, I will try

 

getting your own unit refurbed bypass the need for coding a spare unit.
The website looks like exactly what you need and save $2000 doing it yourself.

 

I'm a bit confused sorry, so is this the better option to get it refurbished? What would YOU do if you were in my situation to get this fixed.

Thanks again for your feedback on this.

 

This is a commonn failure of the ISM/DSM due to low voltage. You can fix it without replacing it but you need to read eeprom data directly from board, repair data, reset mechanical park, reset variant coding with Xentry and then perform calibrations.

 

Does my whole car have to be at a shop for this to be done? Or can I ship out my module to someone to do it? Thanks

 

you've found what seems like a perfect service website.
$350 to refurb this fancy module: that's great work with honest pricing.
I'd go for this.

Your unit should come back better than factory new.

Getting hold of ISM can be challenging the first time.
It's jamed by the gearbox side. You'll need a long wrench and torks bits... not totally fun but that's saving for your next long road trip.
Well worth couple hours laying down under