Hi all, this is a problem I’ve been trying to solve for months now. I’m at my wit’s end.

It first started about two months ago when suddenly I couldn’t put my car into Drive. The error message on the dash said “Vehicle not in P”. (But it was already in P) The car was stuck like that for a couple of days on my driveway and suddenly it started working again. I checked the faults hoping to get some information and I’ve gotten 1991 1997 and 1904.

What was consistent was the fault codes related to ISM. I took the car to an indy shop that works on a lot of MBs and they were able to run the diagnostics and reset the ISM. Everything seemed to be working after that.

A week later same problem. This time error codes 1978 1974 1904 1908 1903. All related to ISM. And dash error message “Drive to workshop without shifting gears”. I am using code reader iCarsoft specific for MB.

Somehow that evening I was able to put in gear as if nothing was wrong with the car yet again and drove it to the shop.

The shop looked over everything again and recommended this time we replace the ISM altogether. So we did and they reprogrammed the ISM. ISM was sourced from MB.

The car seemed to be fine after this for about a week and again the car was stuck in Park. Same problem. This time we were at a mall and we had to get a tow truck to come and put a dolly on since the wheels won’t turn in Park. Somehow we get it to the shop for the third time.

At the shop now everybody is puzzled. They replace the ISM for the second time (using MB parts warranty) and check to see everything is connected and greased. Mechanically everything seems fine. We also noticed low voltage for AUX battery so replaced that with a new MB battery. I also replaced the main battery with a new battery but not with an MB but with a same spec Kirkland (Energizer brand) battery. Checked CCA and voltage, all checks out.

Now at this point we are skeptical of the car. We drive it for a few days then it happens again. We bring the car back because somehow I was able to put into drive after a while. At this point the shop hasn’t charged me any additional labour/parts beyond the first ISM replacement. I really don’t think they are trying to rip me off here. After couple of weeks at the shop they decide to replace the column mounted shifter and the harness with a new replacement. Apparently there are cases the shifter malfunctions and can’t send proper signal. They replace it for me and the owner of the shop says he will personally drive it around for a week to make sure nothing is wrong. If the same problem persists they will not charge me for the work!

And here we are today. The shop just called me to say the same problem came back. The car won’t go out of Park….

At this point I’m lost. The car is otherwise in great shape. We baby the car. No rust. We keep it very clean inside and out. It is daily driven at 250,000 KMs. Regular maintenance done on time, etc. Transmission fluid and filter was replaced about 20,000KM ago.

I gut feeling is it’s a minor issue that may be overlooked? The fact that everything works fine for a week or so until it happens again is the most frustrating part.

I’ve checked the forum and on YouTube and I see people with similar problems. They’ve all seemed to have fixed the issue somehow with some basic replacement of parts such as ISM, shifter, reprogramming, etc.

I don’t know what to do and I’m thinking of salvaging the car which I really don’t want to do. It’s been a troublesome 2 months and a source of stress.

I’m asking the forum for help or recommendations… anything will be greatly appreciated.

Thank you for reading!

 

found this info on *******.com
”removed the new ISM, and using the GBOX i was able to see the ISM Vehicle information (which had the right vin number etc) and i saw the ISM KEY INFORMATION, which only reflected HASH data and didn't make too much sense by just looking at it.

i left GBOX and all wiring plugged in, and just took the scanner with the obd2 cable to the vehicle, went on the EZS module and pulled the KEY DATA (which was on the same format as the ISM KEY INFORMATION I had just looked at!) , where i realized the Key information on the EZS was not matching the ISM KEY INFORMATION i had just seem on the ISM while i had it on the bench !!

i made a copy of the EZS data info, went to the bench one last time, clicked on "write data" to the ism and loaded the EZS file i had just created.

ISM was installed once again on the vehicle. Went ahead and did calibration, personalization etc.

Finally did a Transmission Range Selection learning on the transmission module, and vehicle started back on and it was shifting gears perfectly!!

I hope this can help anyone who is having this issue, it took me a long time and tons of research to be able to figure it out, and I know i probably didnt explain myself properly at certain steps, but feel free to ask me any questions, i would happily assist you”

 

Are you able to DM me the source? Please and thank you!

 

Same problem here. Exactly the same, interittant at 1st and then finally trans is stuck or something.
Won't start or anything. Had to have to dragged into the driveway where it has sat for about 6 months now.
Before it got to this stage, I replaced the shift module since it seemed to be throwing codes along with ISM,
but of course ISM is not easily repaired DIY, and shiftt module was a little less than $200
so it was worth a try...and it worked! But just for a little while.
I'm not looking forward to wrestling the ISM out of the trans.
You can supposedly get a used one recoded to your car, or have it repaired.
GF thinks it's my job to fix this major clusterF but I'm not really very good beyond the basics.
One mechanic I spoke to said it sounded like it could be a selenoid in the trans.
You certainly here it when you to take turn the key, and it doesn't sound like it's getting into the correct
position. And of course internal repairs on a trans with ~225K miles on it is probably a huge waste of money.
She just keeps throwing money at this car, refuses to give up. To further complicate things, the left rear door won't open
(not related) and the right rear door is blocked by a tree, when it was towed. So I have to climb over the seats and wrestle with the battery.
I'll maybe try charging it again, and maybe just maybe by some miracle it will have cured itself. Doubtful.
I really hate any benz's after 5 speed. This crap with everything in the trans and computer coded to the car
is f'ing major pain in the ****! And how many thefts has it prevented over the 722.6 5 speed ?
Prior to 2005 you could just swap the TCU, conductor plate or even the whole trans at will.
This crap sux! I hate this car. Balance shafts, power steering pumps, fuel filter in the gas tank, potato chip intake manifold and on and on.
She spent 6 grand+ on the balance shaft with some other stuff, and another 1500 on the fuel pump, fuel filter about 50K mile ago.
All the plastic flaps in dash for air was real fun when they all came apart. Fortunately we saved all the
bits and I repaired/glue it.
So what's a GBOX anyway? Where, how, can I learn to fix this, or pay someone?

 

The only way to deal with older MB’s especially the first generation 7 speeds is to be a DIY or finding an INDY that is good. Examples…$1500 on a fuel pump that cost under $200 is really high labor cost.

 

We moved to So. Oregon coast. Nobody here has Benz's. And hence nobody works on them.
My 02 C230 sat in the rain for 2 years until I could make a space in the garage after much
argueing with the wife about getting rid of things. It had ALL sorts of problems, but miraculously
they all went away after it dried out. Fall/Winter here is 6-7 months of solid rain.
Well now the 02 is in the garage, all fixed up again, new alternator, MAF, starter, supercharger, brakes, tires,
thermostat and shift module, but all things within my grasp. Brakes, thermostat and shift module (picknpull) I already
had sitting for years on a shelf. So didn't co$t tooo much.I'm holding out for the 300K mileage award with any luck.
But this ML just infuriates me. She needs to let it go.
Like Sully. (Arnold reference )

 

Rear lights and sunroof leaks should be looked into. Rear side passenger Sam unit is a notorious problem area.

 

Is everything in the Salon working well when car is tuck in then Parking? Door locks, thrunk, etc? No problem with cranking at any time? Seems a signal loss or a short circuin in Can Buss. I would recomment to use can bus decoder and compare data when car is working and when its not. Youll see there which signals being lost during malfuncrion.

had the same problem and the cause was cracked soldering points inside the ISM. But in my casee i was unable to start the car as well alongside with failure of shifting gears.