722.9 strange issue C Class
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722.9 strange issue C Class
I just bought a Mercedes c class 250 CDI automatic and it turns out that when I travel about 100 km happily an error appears in which the gearbox changes intermittently and randomly between mode e and mode s, and the car jerks coinciding with the mode change. When the car is cold it doesn't happen at all. Tomorrow I have an appointment with the workshop to consult but I wanted to know your opinion, especially to contrast. I forgot to mention that I have connected an elm27 OBD to it and with the torque Android application it gives me errors u0101 and u0002. Thank you so much. Greetings.
Edit: c class coupe 2012 250 cdi.
Edit: c class coupe 2012 250 cdi.
Last edited by lemach; Dec 20, 2024 at 08:53 AM.
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From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
You should read the welcome post. Please identify your location and your car by model, year, and engine. Also, generic OBD readers are mostly useless on Mercedes -- get a Mercedes specific scanner such as the LAUNCH Creader Elite 2.0 BENZ. Lastly, if you are going to post error codes, please look up their meaning and post that as well. You'll get more timely responses.
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U0101 fail to comunicate with tcm
They haven't evaluated it yet, they have to give me an appointment to go in for diagnosis, but they told me that the 722.9 if the ATF hasn't been changed, when it gets hot it becomes more liquid and can affect the connector on the plate... is this so? Has this happened to any of you? I've read something about the Siemens plates being affected by the temperature but I assume that my car being from 2012 won't have that plate, I think
Regards
They haven't evaluated it yet, they have to give me an appointment to go in for diagnosis, but they told me that the 722.9 if the ATF hasn't been changed, when it gets hot it becomes more liquid and can affect the connector on the plate... is this so? Has this happened to any of you? I've read something about the Siemens plates being affected by the temperature but I assume that my car being from 2012 won't have that plate, I think
Regards
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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
I've not heard about hot ATF fluid becoming "more liquid" when it heats up, though it is a property of liquids to become more liquid when hot. All 722.9 transmissions have conductor plates. Sometimes the sensors do go bad. You can try to get the conductor plate repaired (www.circuitboardmedics.com) or replace it with a new one. New plates must be purchased from and installed by the dealer since they must be coded to the car. The dealer will not sell you a new plate without installing it. Figure around $2,000 or more.
Your car is 13 years old. We don't know the mileage, but it doesn't matter if the tranny has never been serviced. If you have the newer 7G+ transmission, it should be serviced around 77,500 miles or 5 years. 7G transmissions should be serviced at 39,000 miles.
Your car is 13 years old. We don't know the mileage, but it doesn't matter if the tranny has never been serviced. If you have the newer 7G+ transmission, it should be serviced around 77,500 miles or 5 years. 7G transmissions should be serviced at 39,000 miles.
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2021 GLB250 FWD, 2023 GLA250 FWD, 2013 C250, 2015 GLK350, 2005 ML350SE, 2003 E320
@JettaRed has the details — U0101 may be the generic problem but a dedicated scanner will indicate more specific problem points. Don’t jump to needing a new conductor plate until thorough diagnosis has been done. If the TCU and ECU are not talking, the transmission will, of course, not work right. The problem could be the wiring harness, the connector at the transmission, the fluid/air connector in the transmission case, or the conductor plate. Please post the specific findings from your mechanic so the best guidance can be given.
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Very good afternoon.
A while ago I commented about 722.9 failures what is happening to me. Today I provide data that I believe is very indicative.
Failure summary: when cold everything works ok. After several km of sporty driving, the gearbox jerks with gear changes and stops responding to the controls and the comfort/sport/manual modes and even the gear/mode indicators disappear from the dashboard.
Yesterday I received my launch x431 creader elite diagnostic machine and today I went to drive the car to cause the 722.9 to fail and that's how it happened; In fact, I have attached links with 2 videos of real-time data that I believe are the most helpful in diagnosis. Let's see if we can find the diagnosis 🤞.
I suspect that the alternator and/or regulator may be failing 🤔; but why does the voltage drop at a certain high temperature and when turning the engine off/on it returns to normal values?
Bug report link:
https://usait.x431.com/Home/Report/r...es/timezone/+1
Real-time data videos (722.9 bug occurred and in progress):
https://drive.google.com/file/d/1XYL...w?usp=drivesdk
https://drive.google.com/file/d/1XXo...w?usp=drivesdk
A while ago I commented about 722.9 failures what is happening to me. Today I provide data that I believe is very indicative.
Failure summary: when cold everything works ok. After several km of sporty driving, the gearbox jerks with gear changes and stops responding to the controls and the comfort/sport/manual modes and even the gear/mode indicators disappear from the dashboard.
Yesterday I received my launch x431 creader elite diagnostic machine and today I went to drive the car to cause the 722.9 to fail and that's how it happened; In fact, I have attached links with 2 videos of real-time data that I believe are the most helpful in diagnosis. Let's see if we can find the diagnosis 🤞.
I suspect that the alternator and/or regulator may be failing 🤔; but why does the voltage drop at a certain high temperature and when turning the engine off/on it returns to normal values?
Bug report link:
https://usait.x431.com/Home/Report/r...es/timezone/+1
Real-time data videos (722.9 bug occurred and in progress):
https://drive.google.com/file/d/1XYL...w?usp=drivesdk
https://drive.google.com/file/d/1XXo...w?usp=drivesdk
Last edited by lemach; Feb 1, 2025 at 05:08 PM.
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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Now that you have a diagnosis report, clear all the codes and see which ones return. I don't know why your TCM does not show up in the report.
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Yesterday before leaving with the car, I deleted all the error codes, we went out with the car to cause the gearbox to fail and several videos were recorded.
I add an edit where you can see the generated DTC codes and what I thought was important.
I highlight the low voltage of the TCM (11.7V) once with the fault (and the car started) and that when turning off/on the car, the TCM recovers 14V but continues to fail.
The battery sensor shows 12.7V with the engine running and the TCM 11.7V. When turning off/on the car, both the battery sensor and TCM show 14V but the fault persists.
Diagnosis report:
https://usait.x431.com/Home/Report/reportDetail/diagnose_record_id/9a42c632ge5454OMoGOMKwtZLr/report_type/D/l/en-us/timezone/+1
https://drive.google.com/file/d/1XzB...w?usp=drivesdk
Last edited by lemach; Feb 2, 2025 at 04:55 AM. Reason: Add diagnosis report
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And now i have erased all dtc stored and the diagnosis show this:
https://usait.x431.com/Home/Report/r...us/timezone/+1
Is it possible that alternator/regulator fails at high temperature and that it cause low voltage?
Screenshot yesterday when the TCM was failed
Screenshot when car is cold and started
Thanks.
https://usait.x431.com/Home/Report/r...us/timezone/+1
Is it possible that alternator/regulator fails at high temperature and that it cause low voltage?
Screenshot yesterday when the TCM was failed
Screenshot when car is cold and started
Thanks.
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Correct link to diagnosis report while TCM is failing
https://usait.x431.com/Home/Report/r...us/timezone/+1
Correct link to see video
https://drive.google.com/file/d/1XzB_Omz5yJOQIT7xRQFaiEZi6VATOrOO/view?usp=drivesdk
I am waiting for your help, please. Thanks a lot.
https://usait.x431.com/Home/Report/r...us/timezone/+1
Correct link to see video
https://drive.google.com/file/d/1XzB_Omz5yJOQIT7xRQFaiEZi6VATOrOO/view?usp=drivesdk
I am waiting for your help, please. Thanks a lot.
Last edited by lemach; Feb 4, 2025 at 01:36 AM.
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Nobody can tell me about this problem?
I have an appointment with the official workshop next Tuesday but I was hoping for some guidance or experience from you to understand what is happening and compare the information with that of the mechanic. Greetings and thanks.
I have an appointment with the official workshop next Tuesday but I was hoping for some guidance or experience from you to understand what is happening and compare the information with that of the mechanic. Greetings and thanks.
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Mercedes C230 1997 W202
+1 for possibility of voltage regulator not regulating correctly for the upper voltage.
As per your screenshot, an alternator should put out peak voltagw sub 15 volt, depending on battery atate of charge. Screenshot show a much higger charging voltage, if it is indeed the charging voltage shown for that field in the tool. Electronics tend to show their faults more when warm.
Cold start car, check voltage as it warms up in idle? If starting with a fully charged battery the charging voltage should gradually decline.
As per your screenshot, an alternator should put out peak voltagw sub 15 volt, depending on battery atate of charge. Screenshot show a much higger charging voltage, if it is indeed the charging voltage shown for that field in the tool. Electronics tend to show their faults more when warm.
Cold start car, check voltage as it warms up in idle? If starting with a fully charged battery the charging voltage should gradually decline.
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This video describes tranny fluid as thickening when it gets too hot. I imagine it's something like egg whites becoming solid when cooked.
https://youtu.be/k-FrRyj9FQU
https://youtu.be/k-FrRyj9FQU
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Yes, they do. Mine actually never goes above 180°F. The video was going back to the comment that transmission fluid thins out with heat. While that is generally true, it seems that too much heat can damage the fluid.
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I see, that is good then, think both of us are fine, as it is way below the danger zone.
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Finally, it seems like the gearbox problem has been fixed, except now it jerks when shifting from second to third gear in automatic mode... when I use manual mode, it doesn't seem to, and I say apparently because I've only had it for two days 😅; I've been told it's normal and that it should smooth out over time, although I have the feeling it hasn't adapted properly to the shift. I'm attaching a screenshot of the TCM module information that the diagnostic machine gives me. This TCM module is the VGS 3, right? From Continental? The board that isn't as affected by heat, right?
Thanks again.
Thanks again.
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2014 c300 w204.080 3.5 v6
You can do a relearning with a good scanner. It will take a road trip and hitting shift points while driving. And there is a downshift/coast relearning too. You should do both of those and you will prolly see a significant positive change.
Most of the time you should never feel ones of these transmission shift at all.
Most of the time you should never feel ones of these transmission shift at all.
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Finally, it seems like the gearbox problem has been fixed, except now it jerks when shifting from second to third gear in automatic mode... when I use manual mode, it doesn't seem to, and I say apparently because I've only had it for two days 😅; I've been told it's normal and that it should smooth out over time, although I have the feeling it hasn't adapted properly to the shift. I'm attaching a screenshot of the TCM module information that the diagnostic machine gives me. This TCM module is the VGS 3, right? From Continental? The board that isn't as affected by heat, right?
Thanks again.
Thanks again.
