[Dave2302]

can this still be a symptom of bad speed sensor?

I doubt it, but simply cannot be certain as the diagnostic is not on SDS !!

From the available info it would suggest you have an issue with the ISM or the ESL, possibly the CAN wiring.

That's the best info I can give you based on the info you have given. ISM is definitely a Theft Relevant Part (Immobiliser), and perhaps the Selector may be as well.

These Theft Relevant Parts are very advanced jobs for DIY, cannot be purchased from MB by an individual, and almost impossible to Initial Start or Clone unless you have the correct Equipment, (SDS or programming/ cloning equipment) and even then you need a fair bit of knowledge to Program them successfully. I've, (luckily) never had to do an ISM .................

@Deplore knows a lot more than I do on this subject and may be able to comment /correct me if wrong, that is if he isn't too busy

HTH

 

[samir]

Hi Mates!
Recently my baby didnt want to change gears. Stuck at 2nd or 3rd. Pulled over and restarted the car. All ok again. Shifting was rather smooth as usual. But I know it will be back again. I quickly researched here for answers. Everyone pointed to conductor plate, speed sensors as the usual suspect. I connected good old iCarsoft and diagnosed. There are 2 speed sensors Inside the tranny. Yn/6n2 and Yn/6n3. I drove around and recorded the rpm. Sure enough there are times that 6n3 reported 0 rpm when 6n2 reported a plausible one.
View attachment 608770
Most resources I saw on the page deals with the 7G tranny. Mine is a 5 speed. I hope I don’t bother you guys too much with The following questions.
1. Are the speed sensors in the 5G tranny as problematic as the ones in the 7G version? I cannot see anyone selling speed sensors for 5G tranny. Only 7G. At least not in ebay.
2. What is the reason for having 2 sensors? Redundancy?
3. i see a lot of people selling conductor plates WITHOUT the TCU and solenoids. Any opinion in these?
4. I would rather just replace the speed sensor and maybe the solenoids, I dont want to mess with the TCU. Is that possible?

thanks a million guys.

Bryan

View attachment 608771 Pla

hi
i changed the 2 sensor in my cp 722,9 from about 2years and everything work great without changing the tcu ,and its not so difficult ,and i have buy it from amazon
regards


Sent from my iPhone using Tapatalk

 

[Dave2302]

i changed the 2 sensor in my cp 722,9

All very well and good but all the info above says this is an R171 with 722.6

Current info in post # 20 and first photo in OP suggests it has nothing to do with Speed Sensors !!

 

[BSY]

does the 722.6 ( 5 speed) have an ISM? Trying to google for now.

 

[Dave2302]

Now that I cannot answer, yes 722.9 has one, but personally I've never seen one on a 722.6, however it may have one as most R171's had 7G .........................

Or, the iCs might well be telling lies, which is exactly why myself and others recommend SDS for proper Diagnosis.

Question, does your Transmission, on left side have a Lever like this picture below with a Rod attached to select the Gears .............



If it doesn't, and it has an Aluminium Box with a Wiring Plug attached then it has ISM

If you don't have ISM, then it is possible the iCs is referring to your Selector Lever and it's communication to the TCU, but all bets are off until you get the Car on SDS, I can't second guess a dumb OBD Machine they are all known for telling lies and leading many an owner up the garden path

 

[BSY]

Now that I cannot answer, yes 722.9 has one, but personally I've never seen one on a 722.6, however it may have one as most R171's had 7G .........................

Or, the iCs might well be telling lies, which is exactly why myself and others recommend SDS for proper Diagnosis.

Question, does your Transmission, on left side have a Lever like this picture below with a Rod attached to select the Gears .............



If it doesn't, and it has an Aluminium Box with a Wiring Plug attached then it has ISM

If you don't have ISM, then it is possible the iCs is referring to your Selector Lever and it's communication to the TCU, but all bets are off until you get the Car on SDS, I can't second guess a dumb OBD Machine they are all known for telling lies and leading many an owner up the garden path

i cant seem to get to see that part of the tranny without lifting the car. i do rember that before this all started, there was one time where starting fresh, I shifted the car into reverse and car stayed in neutral!
i restarted the car and all became well and I forgot about the incident. This I believe has nothing to do with speed sensors. I saw that N15 photogates can get desoldered.

I am hoping to god that this is the cause of my problems. I am an electronics engineer by trade and something like this is very familiar to me. I wont have issues fixing/rebuilding a board like this. But i dont know if this board going bad can cause your gears to get stuck in 2nd or 3rd WHILE driving.
note that generally shifting is rather smooth when vehicle is running, it just decides to stay in one gear when it happens. Gear display on the dash does NOT turn blank or anything when it happens. While running and gear seems stuck I try to manually change gears nothing happens. Dash display always stays at D, wont display 4, 3, or any other number.

 

[BSY]

As you have info for the tranny/conductor plate, now is a good time to read the ABS sensors speed/rpm numbers. If any is missing you know what to search.
But because of the conversation do you have active diagnostic of any kind on that scanner of yours?
Just curious, nothing else.

iCarsoft v2 MB seems to be ok with the live data feeds from tranny. I have the rpm speed sensors, solenoid currents, actual and intended gear positions.

 

[BSY]

Ok. Update again. Sorry if I wasted all your time from being a noob. There was another DTC code. It was hidden in another part of the iCarsoft menu so I missed it. Its P1856.

Dave2302 again got it right. Nothing to do with speed sensors. Its the shift lever. I also moved it around and checked the iCarsoft, “requested postion” vs my actual physical position and the switch is sluggish. Time to open this baby up. i don’t have to get under the car! woohooo. I don’t need to get grease and oil all over me. I’ll report progress in a few days. Thanks.

Bryan

 

[BSY]

Any advice will help. I.e. do I disconnect the battery first in order not to throw whatever code or activate any anti theft features? I intend to remove the board, resolder suspicious joints, probably replace the propably old electrically (and maybe physically) leaky electrolytic capacitors while I’m at it.

 

[Dave2302]

I never disconnect Batteries on MB or other Cars with many electronic Modules, it very often causes more grief than it is worth. I don't even power a Car down when changing a battery !!
Just remove the Plug(s) from the the Relevant Module and wrap them in a Plastic bag whilst working. Use due diligence not to allow anything to short out or get wet etc etc

If there is more than 1 plug, I un plug the one powering the Module first and when refitting I plug that one in last. Most Modules won't flag a Code unless the Ignition is on !!
Part of any work on Vehicle Electronics is to clear all Codes generated after work, so don't worry about that ............... Most garage mechanics do not clear codes, that is just because so many are clueless / don't give a hoot

No one will never convince me how "good" an iCs is for proper diagnoses at this level, because these and many others have been tried and tested by myself and others in this trade they are simply not seeing or doing everything, some more so than others

Yes, an iCs is a useful and compact unit to stick in the boot of a car on road trips, and it may help the owner to decide if OK to continue the journey in the case of an ABS / Transmission / Engine etc light has just come on

 

[BSY]

Agree on the SDS. how musch does something like that cost?

 

[Turbo]

Agree on the SDS. how musch does something like that cost?

"Quite a bit"!

But if you only think you'll need it "once in a blue moon", I wouldn't bother.. Just take it to a MB specialist (!!) and have them read it for you. Here, it's about £50 and you get a nice printout with EVERYTHING! Old, stored and new faults. They even interpret it for you..

For that kind of money, you'll going to have to use it A LOT (!!) for it to pay for itself..

 

[BSY]

Too good to be true? I was prepared to spend this weekend disassembling the center console to reach the shift lever. But I couldn’t resist taking a peek. It really looks like I can simply remove it by just removing the centre panel. so far I didn’t even need a screw driver. Or am I going to regret this later? Question: i know there is a cable at the bottom of the lever which places the vehicle on park. How do you remove that pls? Thanks a million guys!

 

[Dave2302]

If you own a Mercedes that is more that 5 - 7 years old you will use it way more than once in a blue moon
For £50 you are only getting a single read and many many don't give the print out, (which I hate, I always give at least 2 print outs car in, clear all the dross, road test and re read, final print) ..............
When you get into more advanced diagnosis features od SDS such as Guided testing and Graphing data etc etc it can easily run 2-3 hours of workshop time to nail the fault.

It costs around £500 - £700 depending upon how much work you are prepared to put into it yourself, for example preparing a good used Laptop / Tablet with a decent spec, fresh Windows Install etc.

SDS pays for itself very quickly, for many reasons, I have typed reams on this before just search the Forum.
If you ever go away from Mercedes vehicles you can usually sell it for around what you paid.

There will always be the "SDS nay sayers"

There are some guys on here who will, since they got SDS, testify that there is very very good reasons to have it despite it being dearer than the extremely lacking OBD stuff on sale that is very over hyped in it's advertising.

I have several Generic Professional Workshop Machines, Autel Pro and Snap-On being the 2 I use the most, they cost between £2200 and £7000 and whilst they are good, especially for speed on all makes of vehicles with run of the mill everyday issues, such as a bad ABS Wheel Speed sensor, SRS light on, Service Indicator resets etc .....................

Mercedes wise SDS is still far superior !!

SDS costs 10% to 25% of the cost of those Pro machines, same applies to all the other "Dealer Level" Kits I have such as VAG Com for VW's, Peugeot / Citroen Lexia, Toyota Techstream, Ford IDS, Renault CAN Clip, JLR etc etc etc.

HTH with an informed decision

 

[Dave2302]

I believe the Cable is push / twist, it is on many 722.6 Shifters .............. You just need to look carefully to see how to release it.

You will also need to get under the car and release the Selector Rod, which often entails removing Undershields etc to release it without bending it.

SDS also has WIS (workshop manuals) on it btw

 

[Turbo]

If you own a Mercedes that is more that 5 - 7 years old you will use it way more than once in a blue moon

Yeah, ok. Fair enough.

Mine's eleven and I got my SDS after having had issues with the air con. Back and forth between different MB "specialists" (I put that in citation marks, because it turns out they wheren't as good as indicated).

I got that sorted eventually, but figured I spend the £££ on my own SDS anyway, just in case. I've been lucky, knock on wood, that that (air con issues) seems to be the extent of my actual issues with the car. I'm sure it'll get worse over time, but so far so good..

Having your own SDS DOES give a few extras. IF YOU'RE CAREFUL (!!). There's things in there that is nice to play around with. Throttle response, complete and "real" reset of the gearbox and what not . AND, if there's even the slightest issue, or imagined issue, then just go in and get the SDS and of you go - you'll know in minutes (instead of having to drive somewhere, wait for your turn, have the read etc etc etc) if there's an actual issue.


I'd rather spend the three, four times the money on SDS than on iCarsoft or any other OBD reader! Because they give a false sense of knowing - they don't give you the WHOLE picture!


But in retrospect, that money was mostly wasted. So far..

 

[BSY]

I believe the Cable is push / twist, it is on many 722.6 Shifters .............. You just need to look carefully to see how to release it.

You will also need to get under the car and release the Selector Rod, which often entails removing Undershields etc to release it without bending it.

SDS also has WIS (workshop manuals) on it btw

Get under the car? Hmmm. Thats a no go for me. Ohh my.

 

[Sneaky Pete]

Question: i know there is a cable at the bottom of the lever which places the vehicle on park. How do you remove that pls? Thanks a million guys!

You mean this cable? See attachment.

 

[Dave2302]

That's the one, cheers Pete

To OP, be very careful just pry that little tang outwards very gently then turn the plasic and release it I've seen some break off very easily

 

[Dave2302]

Oh BTW, that cable allows you to get the Key out of the EIS when in Park or Neutral, so when released you cannot get the Key out without pushing in the end of the Cable until Key releases, don't leave that Key in EIS, some MB's will drain the Battery overnight if you do