MERCEDES BENZ 3

2006 MERCEDES C230 SPORT
Transmission 722.9 7-speed
VGS 2
Various owners before me
135,000 MILES
CALIFORNIA

SCANNER: AUTEL MD802 - MAXI DIAG ELITE - ALL SYSTEMS DS (ALL MODULES)
This scanner will scan ALL MODULES, but CAN'T PROGRAM or ACTIVATE SENSORS, NO ADAPTATIONS.

LIMP MODE - ONLY 1st and 2nd gear
CODE 1789 Fault in control module Transmission (P0730) MIL ON & STORED
CODE 0894 The gear in implausible or the transmission is slipping STORED

Hello forum members:

I am new in this forum and this is my 1st post. Please help me!!!

My 2006 Mercedes C230 is currently in LIMP MODE, it only works in 1st and 2nd gear, as soon as it is time for 3rd gear to engage, RPM jumps, then I release the accelerator so it won't make more damage by slipping out of control.
But if I press again the gas pedal, I get to hold 2nd gear at higher than normal RPM, going only at 10-15 mph. Of course I could press for more speed, but RPM will jump into the 3000 rpm or more.

HOW THE PROBLEM STARTED:
Car was driving perfect at highway speeds of 65-70 mph, up-shifting and down-shifting perfectly, for 1 hour.
When I got home, I turned around the car in front of my house, in a residential street at extremely slow speed, to let a family member continue using the car, when all of a sudden, I noticed the car wouldn't roll. When I released the brake pedal, the car wouldn't move, when I push the gas pedal it was very heavy, moving it required more power.
I thought it was something to do with SPORT / COMFORT shifting, I changed the setting with the button, but I got NO CHANGE.

I gave the car to a family member warning him about the unusual car behavior. Later, he said he noticed some heaviness right at the corner of the street, after that the car was fine, he said. His trip was short in residential streets at 35 mph max. He felt the problem again for a moment while turning (heavy rolling) when he arrived at his destination, 8 minutes later.
An hour later he called me when he couldn't move the car. He put the car in NEUTRAL and push it, but it was like braking, no move.
I went to help him, scanned the car, but got NO CODES, NO ENGINE LIGHT. I scanned ECU and Transmission modules only.
I was suspicious of a WEAK BATTERY, I was having sporadic small incidents with battery discharging.

Since it was a short distance to my home, I forced the car to move, and while doing that I smelled something burning. I thought it was the CLUTCHES in the transmission, since I know there are 2 BRAKE CLUTCHES PACKS inside the transmission.
I move the car at 10 mph, extremely slow, for 1.5 miles only, monitoring the TRANSMISSION FLUID TEMPERATURE NOT TO EXCEED 175-195*F
At one point I stopped to wait for the transmission to cool down.

In the meantime, I decided to do an ECU RESET by turning ignition to the ON POSITION, pushing gas pedal to the floor, waiting for 1 minute, turning OFF THE IGNITION, releasing the gas pedal, waiting for 2 minutes to start the car, or something like that procedure.
Somehow, by doing that, the braking, heaviness disappeared and I was able to move the car at a better speed, but I noticed the car was in LIMP MODE.
I got home and scanned it again, NO TRANSMISSION CODES, NO ENGINE LIGHT ON.

Before the problem started, it was always my intention to do a TRANSMISSION FLUID AND FILTER CHANGE (NOT A FLUSH), so a few days later I did it, thinking that it may solve my problem. I was wrong.

FLUID DARK OR BLACK, BUT NOT BURNT, NO UNUSUAL SMELL
NO FILINGS, NO METAL in the magnets
REMOVE FLUID FROM TORQUE CONVERTER
FLUID LEVEL WAS CORRECT, I think 9 QUARTS

In my opinion, THIS WAS THE FIRST FLUID CHANGE AT 135K MILES
ALL SOLENOIDS were checked for resistance and function, they were within range and clicked with battery voltage.
ALL SOLENOIDS were cleaned with a magnet and brake cleaner
ALL 3 SPEED SENSORS in the conductor plate were cleaned. No filings or unusual gunk.

TRANSMISSION CONNECTOR was cleaned with electronic cleaner.
TRANSMISSION FLUID WAS FILLED at the correct level at the right temperature.
VALVE BODY WAS NOT OPEN, just cleaned the upper and lower surface, NOT DISASSEMBLY.

During all this time frame, the car battery discharged and it was changed for a new one. But with that time, the new one discharged also, so many times I recharge it and disconnected the battery.

The car is still in LIMP MODE.
Now the car was showing 2 codes that were HARD CODES in the ESP MODULE (ABS).

Code C1130 L6/4 (right rear speed sensor) : Line monitoring
Code C1120 L6/3 (left rear speed sensor) : Line monitoring

HARD CODES because the codes could NOT BE DELETED, not with my Autel MD802

I went to a transmission mechanic who wouldn't work on Mercedes, but agreed to use his latest Snap-On scanner. He was able to delete the REAR SPEED SENSOR CODES in the ESP module.
I thought my car was OUT OF LIMP MODE, but I was wrong.
Car is still in limp mode.

Codes 1789 (P0730) MIL ON & STORED and 0894 STORED only appear if I move the car, and I can DELETE them.

I need to get the car out of limp mode, smog it and start using it again.
Please I need help from anybody who may have experienced something similar. I need help especially from all the experts in this forum.

Thank you.
p.s.: Sorry, I know it is a long post, but has ALL the details.

MERCEDES BENZ 3

Come on, guys!!! 12 hours from the original posting and nobody has some solution for my problem?
I thought by including all necessary info I would get a quick reply... but so far nothing!

Please I need your help.
Thanks in advance.

MJ50

moved to W203 forum...

MJ50

you originally posted in wrong subforum...

MERCEDES BENZ 3

Sorry, it wasn't clear how to post to the W203 forum, I looked and tried but didn't do it right.

Thank you for your help.

BenzPR

Hello OP,

i know this is an old post, but having this same problem. Can you tell me what was your solution ?

thanks in advance

MERCEDES BENZ 3

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Hi @BenzPR , sorry about not replying to your question sooner. The reality is that I am disappointed about the lack of feedback from forums members, except for @Rudeney , who was very nice to try to help me at the time. I waited for a long time to hopefully get another member to give me options to repair this problem, but got no response. Due to that fact, I kind of stopped checking my email acct associated to MBWorld.org, then I didn't see your request. I am replying almost 20 days later to you because I hate when people don't reply to questions in forums. So here is where I am with this problem at this point:

Of course, I can't use this car, I have another cars that I use. I went to have Aamco Transmissions check it out, they told me I lost 3rd gear. They didn't disasemble, they just scanned it I think with Snap-On scanner, and test drove it. They didn't let me see what they did to check.
They asked me for $4,500 to rebuild it. BUT I DON'T BELIEVE THEM. I won't spend more money than what the car is worth.

Why I don't believe Aamco? Because as I said before, after I started with this problem, I thought I would fix the transmission by I changing the fluid and filter, and removing the valve body to visually inspect the solenoids, conductor plate and 3 speed sensors. I DID NOT OPEN THE VALVE BODY, did not separate the upper and lower halves of the body, only removed the solenoids and cleaned them with a magnet (there were NO metal files to clean in them) and with brake cleaner. I noticed the o-rings in the solenoids came out in pieces, totally destroyed, so I had to put new o-rings. Clearly, they were the original ones since new, after working for 135,000 miles. But I also noticed some pieces of the old o-rings where missing, probably stucked inside the valve body (Is this my main problem???). But as I said, I DID NOT OPENED THE VALVE BODY.


I didn't believe Aamco when they said I lost 3rd gear, because I was the one who removed the transmission pan and all the fluid when the limp mode started, INCLUDING THE FLUID FROM THE TORQUE CONVERTER (mine has a small drain plug), and I did not find ANY METAL FILES in the fluid and in the internal magnets. I found only the normal black goo, like a black cream in the magnets, but not an unusal amount of it. I compared to millions of videos on YouTube that I watched.

Yes, the fluid was black, but not unusual color or viscosity with this mileage. If Aamco was right, I SHOULD HAVE FOUND SIGNS OF DESTRUCTION OF THE 3RD GEAR, but I found nothing like that. ALSO, THE FLUID DID NOT HAVE ANY BURNT SMELL.
I also want to point out that I have experience disassembling a valve body from a 1989 BMW 735i E32 with a 4HP22 electronic transmission, where I found, as expected, 2ND GEAR TOTALLY DESTROYED, so NO FORWARD, NO MOVEMENT IN THAT DIRECTION, BUT ONLY REVERSE WAS OK, and the magnets in that transmission looked like a Chia Pet with files, jajaja!!!

I continued to research about this problem, and I think I should go back to the source of the problem: Everything started with a car that seemed to have the brakes applied, I would put the shifter in NEUTRAL but the car would NOT ROLL. When I would put it in DRIVE, the car would move but it felt VERY HEAVY, LIKE BRAKING WHILE ACCELERATING all at the same time.
I am very suspicious about the ABS MODULE. The first scan I did at the time, I didn't think about ABS, I only scanned the Transmission and the Shifter. I knew my battery was in its last leg, sometimes when I didn't use the car for 2 or 3 days, the battery would discharge, but that day seemed to be good, but still, I WAS SUSPICIOUS OF THE BATTERY.

So, I immediately changed the battery thinking everything was going to be back to normal, but I was wrong. AFTER CHANGING THE BATTERY, any other codes or DTC'S in other modules were deleted, if any. That night when the problem started, I did a transmission reset while trying to fix the problem, the procedure is described by everyone in all Mercedes forums, and after that reset, the car started "rolling normally again", no heavyness, no feeling like the car had the brakes applied, BUT IT WAS ALREADY IN LIMP MODE, THE CAR DID NOT ENGAGED IN 3RD GEAR OR ABOVE. After that, I was able to move the car for 1 mile to my house, without overheating the transmission that I was monitoring its temperature with my Autel scanner.

After many test drives and scans, I noticed the 2 codes in ABS module, showing problems with speed sensors. After changing all 4 wheel speed sensors and not being able to take the car out of LIMP MODE, I am also suspicious of the the 3 speed sensors INSIDE THE CONDUCTOR PLATE, not unusual to have problems with those sensors at this mileage. The problem is that the codes or DTC'S don't point to those inside speed sensors.

I think maybe the ABS module has some cracked solders and malfunction on and off, intermitently, or an ABS PRESSURE SWITCH is malfuctioning, again NO CODES for that.
Another posibility is that all that DARK BLACK FLUID made at leat one or more solenoids (maybe solenoid 2-3 gear) STICKY and may need replacement. That is a real posibility.

There are some clutches inside the transmission that are brake clutches, B1, B2 , but I don't think they are malfunctioning or destroyed because I did not find signs of that in the fluid.
Like I said in my original posting, NOW the ABS codes are NOT coming back: Is it because the car is in LIMP MODE and it is not being driven, or it is driven very short distances to trigger any codes, only good to evaluate LIVE DATA and look for a solution?

I also noticed the ALARM is showing a code, and maybe since it is a DEFTH ALARM, it is affecting the CAN BUS??? (this problem appeared apparently at the same time the transmission problem started) Any German car technician will tell you to fix all other current codes in modules supposedly unrelated, before you start fixing the main problem, in this case the transmission? or ABS?

When I scanned all the modules, the scanned shows that IT IS NOT IN LIMP MODE, but in reality, live transmission data while driving shows gears changing normally from 1st to 2nd, but it would not engage 3rd on, then stays in 2nd.

One theory I have is that being the battery weak, maybe all modules received an amperage peak and damage or at leat put it in limp mode the transmission control module TCU inside the valve body. In many forums Mercedes experts many times claim that many DTCs or Limp Mode will ONLY BE DELETED OR FIXED BY USING XENTRY / DAS MERCEDES scanner. Is this true? How about Snap-On, Autel, and any other reputable brands?
Maybe I will buy a used ABS module and try that, and/or replace solenoid 2-3 gear, the pressure solenoid and the torque converter solenoid, or ALL OF THEM, all 8??? Of course I would buy used solenoids.
I am also willing to change myselft ALL 3 internal speed sensors in the transmission conductor plate, in this case I will buy new.
I could also send my conductor plate for repair after $250-$300 fee. That's another posibility.

VERY IMPORTANT: I will finish this very long post by saying that I believe transmission problems in these forums should NOT be classified per chassis code, like W203, W220, W221, W204, etc. All Mercedes 722.9 are the same and behave the same, no matter if they are installed in a W203, W220, W209, etc.
How do I know all transmission are the same? Go to FCP Euro or Pelican Parts and the solenoids for one chassis is the same part # than for another one, I believe the same situation for conductor plates. The classification should only be 722.9 transmission, 722.6 transmission, etc.
I read hundreds of forums postings about 722.9 problems regardless of chassis code, and they all behave the same. I think what's different is the programming they have for different engines and chassis. I also have a W220 S500 with a 722.6 transmission, same situation.
In my situation today, I would say that I probably would have gotten more feedback about my problems with my 722.9 tranny if experts or gurus in this forum reading postings on other chassis would have read my problems with my W203 C230.

MY SUGGESTION FOR FORUM ADMINISTRATORS: Transmission problems should be classified by 722.9, 722.6, etc., not by chassis code.

Please if anyone can provide a solution for my Limp Mode problem, please reply to this posting. I will appreciate it very much.

Thank you to all who read this posting.

BenzPR

Thank you for your answer. I completely understand your point of view on this topic.



To give you a little bit of help I will tell you about the things I’ve done to my car.



1- Changed Trans fluid and filter ( no sings of metal ) & verified with correct temperature.

2- Installed & programmed new TCU.

3- Removed and cleaned ( without opening ) Valve body

4- Cleaned and tested all 8 solenoids. All are within specs and all 8 solenoids clicked when applying 12 volts. During solenoid inspection I saw that one of the solenoids bottom filter was a little bit off. Maybe some of the filter broke loose and caused the problem ?

• I really think that both of our problems can be fixed with a new ( or used ) valve body. I saw that the filter under one of my solenoids was missing a piece of the filter (super small but can cause the problem if it gets caught inside the valve body). And you said that you saw something similar but with the o-rings.

Funny enough I too have an ABS code but I think that is being caused by a broken cable. When this problem started I didn’t have an ABS code. So I think this is unrelated to the problem.