How Do I Get The Trans Out Of Limp Mode

[mbclassics]

I cleared the codes with a typical hand held scanner but the trans is still in limp mode. Is there another "trick" to doing it? Or just need a Star Diagnostics? Thinking maybe the car just had a hick up and would be fine if I cleared it. If not then I would get into the valve body. My codes were P0720 output speed sensor and P0500 vehicle speed sensor. 2000E320 Thanks

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[RichardM98]

The purpose of the "Limp Home" mode is the protect the transmission from further damage. You can not clear transmission codes with a OBD II scanner. If it was a 'hiccup' it would clear itself. See dealer or fully equipped indie.

[mbclassics]

Originally Posted by RichardM98

The purpose of the "Limp Home" mode is the protect the transmission from further damage..

I kinda knew that. I just wanted to reset and see if it came back. Read on hear that some reset and never had the problem again. Just trying to narrow down the cause.

[alpinestar_k]

for what it's worth I experienced same issue on old 00E320 - tried batt reset and scanner reset - no luck. Speed sensor was my culprit - best of luck

[wifiremed]

I think your going to have to have it re-set by someone with the STAR system... I just had this same problem... I was having problems with the trans going into the soft limp mode where it stays in the last gear it was in until you shut the car off and restart. (Classic Conductor Plate Failure...) I out smarted myself by trying a coasting re-start. That was the wrong thing to do because it locked me into hard limp mode... All I had was 1st gear & reverse. I changed the conductor plate and still had the problem. I had to have the car towed to a local private repair shop that has the STAR system. $75.00 later the code was out and everything was back in order. So long story short, once your in the hard limp mode you need the STAR system to reset that code. Good luck and check with a local private shop that will save you money over the dealer.

[wifiremed]

I re-read your original post, sounds like you need to replace the conductor plate if you haven't done so already. Others have had good luck and as soon as the plate was replaced the code cleared.

The way you can tell the difference between a hard limp mode and a soft is by the way the car shifts. In the hard mode it really clunks and hammers into gear. It feels like the trans is tearing itself apart. In the soft mode it just stays stuck in the last known gear.

What's happening as I understand it is that the two speed sensors in the trans compare the speed of the input shat to the output shaft to determine what gear the car is in and if it agrees with the commanded gear from the ECM. If the ECM can't get data from either of the speed sensors in the conductor plate it goes into limp mode. This is why sometimes just replacing the conductor plate fixes the problem unless a hard code has been set because then the ECM gets the data it needs to determine the gear setting and it goes on it's marry way. If the hard code is set though and it's in hard limp it won't come out until the code is cleared by the STAR system... Hope this helps!

[fifthndice]

I own a 2003 E320 with 73000 miles on it. It is in what appears to be limp home mode. I had it towed to my local MB dealer and they said I need a new transmission. Car has been serviced properly and no problems up to this point. Car has been sitting for one month. Attempted to move it recently and it went into gear fine with no problems. Afraid to take it on the road as it may go into limp home mode again. From reading other post it appears that may be the car needs a new conductor plate??? Very car illiterate so any help is greatly welcomed.

[Plutoe]

Originally Posted by fifthndice

I own a 2003 E320 with 73000 miles on it. It is in what appears to be limp home mode. I had it towed to my local MB dealer and they said I need a new transmission. Car has been serviced properly and no problems up to this point. Car has been sitting for one month. Attempted to move it recently and it went into gear fine with no problems. Afraid to take it on the road as it may go into limp home mode again. From reading other post it appears that may be the car needs a new conductor plate??? Very car illiterate so any help is greatly welcomed.

If the car were mine, I would ask the dealer to give me the diagnostic print out for the transmission scan.

With that data I would know what was wrong with the tranny and then plan a course of action. Good Luck

[Musikmann]

That dealer is evidently only a parts changer and greedy to boot. They stand to make much more by replacing it than opening it up and replacing necessary parts. I'll bet money that it is repairable and might be something quite simple. A lot of people have replaced conductor plates but there are a few other things that might be wrong. At your tender mileage I doubt that it's anything too serious. From what I remember reading, most people with serious problems are at 100,000 miles and beyond.

As advised get the print out (you paid for the diagnosis didn't you?) and post the codes here.

[fifthndice]

Originally Posted by Plutoe

If the car were mine, I would ask the dealer to give me the diagnostic print out for the transmission scan.

With that data I would know what was wrong with the tranny and then plan a course of action. Good Luck

I contacted my local dealer to which I towed my E320 for the diagnostic printout. There were no codes listed, only what I told the service person over the phone. I have phoned the dealer to request the codes for this diagnostic evaluation for which I paid. I'm waiting for their reply.

I have one other question for you and that is what does STAR stand for?

[Plutoe]

Star is very old terminology for the MB diagnostic system.

The current terminology is DAS Xentry, DAS is is the diagnostic portion and Xentry is the control unit programming portion of the software. However the term Star has become common just like Xerox for copying.

My question to you is "what tools did the dealer use to make the determination that the tranny was junk.

If they used DAS, you can print out the diagnostic report, they are not easy to read, but it's better that the ole blowhards response!! Good Luck

[NJProTech]

Originally Posted by Plutoe

Star is very old terminology for the MB diagnostic system.

The current terminology is DAS Xentry, DAS is is the diagnostic portion and Xentry is the control unit programming portion of the software. However the term Star has become common just like Xerox for copying.

My question to you is "what tools did the dealer use to make the determination that the tranny was junk.

If they used DAS, you can print out the diagnostic report, they are not easy to read, but it's better that the ole blowhards response!! Good Luck

This is correct. Especially the fact that a transmission only gets replaced for a specific or group of specific reasons. Most shops/dealers don't want to risk a rebuild. It's risky in some cases and can be expensive. Sometimes a rebuilt is just better but a simple trans fix could be it all it needs. Adaptation values tell a lot too