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girl newbie,,,,need advice on possible transmission problem!

6K views 87 replies 7 participants last post by  loubapache 
#1 ·
I was told in another forum that I posted to that you guys here know a lot about the 722.6 transmission and to post here, so here I am posting and HOPEFULLY someone can help me, ahhh!

Here is the latest update on my 2004 c320 4 matic

The car threw a check engine code P0715 Input/Turbine Speed Sensor Circuit Malfunction. I've read a little bit up on this code and it looks like it's caused by some electric plate or something. Anyone else have a similar problem with this series?

Every now and then (mostly when the engine is hot) the car will go into limp mode (without the check engine light being on). I've felt a few slips in gear but probably a hand full of times at most.

Thanks!!
 
#2 ·
#3 ·
The P0715 code is a fairly reliable indicator that the input speed sensor is acting up. This sensor is part of the conductor plate so the entire plate needs to be replaced.

Right now, your sensor is only acting up (intermittently) so the Limp mode you are experiencing is the light version, if you will. In this mode, you have third gear only. That is why when you are at stop and want to accelerate, you feel there is not enough power because the gear is too high. After a shutdown, the car will usually shift fine as if nothing had happened but eventually the same symptom will come back.

When it gets worse, it will go to electric Limp Home mode (the bad one) then the car will be permanently locked in 2nd and reverse only. You cannot clear this Limp Home mode without Mercedes or other special scanners.

This job will run about $1000 at the dealer, $700 at Indie, and about $300 DIY. If you have a friend who can help you, there is an entry in the sticky.

If you do this before your car goes into the bad limp Home mode, you do not need special scanner to clear the code.
 
#4 ·
ok, so I think mine might be in the "bad mode" now because my brother read the code yesterday and cleared it, but i turned on my car this morning, went into reverse (car jerked) then went into drive to pull away (car jerked again) and check engine light came on again, so i left my car at home today...

is it bad to drive the car when it's like this or is it pretty much not driveable since the gear is not changing?

also, if the code is cleared it supposedly will be fine again? Is that just temporary that it would be fine and this plate needs to be replaced still?

the dealer is sooooo expensive, ahhhh! is this about $1,000 with labor included?
 
#5 ·
ok, so I think mine might be in the "bad mode" now because my brother read the code yesterday and cleared it, but i turned on my car this morning, went into reverse (car jerked) then went into drive to pull away (car jerked again) and check engine light came on again, so i left my car at home today...
It does sound like it went into electric Limp Home mode, 2nd and reverse only and big jerk when shift lever is moved from P to R or N to D.

is it bad to drive the car when it's like this or is it pretty much not driveable since the gear is not changing?
Since it stays in 2nd gear, you can really only go up to like 40 MPH. If it is for short distance, you could drive it that way (and that is how the system is designed to Limp Home or Limp Dealer :mad:).

However, I would not drive it that way at highway speed.

also, if the code is cleared it supposedly will be fine again? Is that just temporary that it would be fine and this plate needs to be replaced still?
Yes, but this time, it takes special scanner to clear (your brother's may not do it now). Even after you clear it, it will go back into it because the underlying problem is still there. Until the conductor plate is replaced and code cleared, it will be in this loop. Clear code -> drive fine -> back into Limp -> Clear code . . .

the dealer is sooooo expensive, ahhhh! is this about $1,000 with labor included?
That should include labor but as you know, dealers charge whatever they want on a particular day. :mad::mad: As a matter of fact, do not be surprised if they tell you that you need a complete transmission and a transmission control module.
 
#6 ·
Look for a good indie or specialist to replace the electrics plate and save lots of dollars. But change it you must and sooner the better, if you keep clearing the fault code and trying to drive the car you will do far more serious damage.
 
#7 ·
oh of course, "limp home or limp dealer" i get it, makes sense! grrrr!

What's an indie? I know everyone keeps saying this to me, but is this different than a mechanic who specializes in working on mercedes?

yeah dealers can definitely screw you, which I don't like...my mechanic I usually go to is gone on vacation for 3 weeks, so it looks like I have to find another specialist somewhere close by!

Thanks for all your posts to me, greatly appreciated!! :)
 
#9 ·
Yes, "indie" is mechanic who specializes in working on Mercedes but they are not authorized Mercedes dealers. They usually have lower labor rates so they charge less than dealer.

If your brother is a good DIY mechanic and is willing to help, then he might be able to help you.
 
#11 ·
Bo is correct, if your brother can diy, then the way to go is all written here on this forum for him to follow and you will save even more dollars.
 
#10 ·
indie = independent mechanic. Sarah, could you please fill up some info such as your car and location under the "user CP" link? It would be helpful if some experienced member is around your area to offer help.
 
#13 ·
update!

So I havent taken it anywhere yet since most places are very busy and are telling me they cant take my car for another couple days, but the few places i did call and told them what my problem was and then made a couple comments about the posts on here...none of them really knew what i was talking about when i said conductor plate...is it called something different? electric plate?

not to mention, i think they all wanted to know if i myself was a mechanic hahaha...yeah right!

also, is there a chance that there could be more internal damage to my transmission and the p0715 code could just being thrown because there is an error in the computer? Something along those lines is what one place said to me, but he still said he wanted to take a look and jsut wanted to give me a heads up on that...

hope you are all well and thanks in advance for the feedback! :)
 
#14 ·
The conductor plate does have an official Mercedes name. It is called the "electrics kit", however, in the USA, it is often called the conductor plate or electric plate.

Frankly, if a shop does not know what this part is in your transmission, I would try other places.

Although the P0715 is a generic code, it is quite narrow. It is mapped to several Mercedes codes but almost all the time, it is due to failure of the input speed sensor on the conductor plate. There is a possible mechanical failure and that would be the disk that rotates to feed the speed sensor information. That failure, however, is rarer than the senor itself if the transmission does not have too many miles.

The for sure way to diagnose this is to pull the Mercedes codes in the EGS (Electronic Gearbox System) or ETC (Electronic Transmission Control module). Those codes are more specific about the problem.

That being said, the speed sensor (conductor plate) is a weak link in these transmissions. The part has been upgraded at least 4 times.
 
#15 ·
Can anyone tell me the part number for the conductor plate by any chance? I found a website that sells 140 270 11 61 for $180 and just wanted to verify that it's the correct part number for my 2004 C320.

I'm going to do this one on my own versus have her go to a shop. Most of my car work is done on Volvo's and the only thing I've really done with transmissions are PNP switches and a manual swap. After reading a few of the DIY instructions (which were very well written btw) for this particular job, I'm pretty confident I shouldn't have much of a problem. The only problem I foresee is getting the code cleared but I think we should be able to get one of the local shops to help out with that.

Thanks,
her brother
 
#16 ·
OK mister give me your vin number:thumbsup:
 
#19 ·
No problem man, the full vin is required in this case as I am sure you appreciate, it is fairly new.:thumbsup:
 
#20 ·
(brother)
Thanks for replying so fast. We'll get the VIN number posted online tonight but it looks like $130-140ish according to the other thread linked in this thread. Then we'll have to get the filter, gasket, fluid and maybe a few other odds and ends to be safe.

Thanks
 
#24 ·
No mate just a few general managers to fix.
 
#29 ·
(brother)

The parts should be here tomorrow (beside the dipstick which is apparently on back order and they won't have it till Monday).

Is there somewhere else I can get this dipstick by any chance? Even the dealer? Then I could just return that one to parts.com?

Thanks
 
#30 ·
You can even use a flexible wire and there are pictures in the sticky showing the dimension.

As a first step, you can also catch whatever comes out and put that much back in plus just a tiny more (due to the filter). Then when the dipstick comes, you can do a more accurate measurement.

When you do it, you will see the system has a nice protective mechanism to avoid foaming even if the transmission is slightly over-filled. The floater will block the normal return of the fluid to the pan so the gear will not be whipping the fluid. Then the fluid returns via another (higher) opening.
 
#32 ·
I'll be doing the exact same procedure this weekend but I'm also going to replace the pressure regulator spring that's discussed in the stickies.

I was reading up on this thread and it sounds like the tranny is likely to throw a code after the conductor plate gets replaced. Is there any way to clear the code without the fancy dealer software? I'm going to be doing this on Saturday and the dealer wouldn't be able to do it until Monday, if they would at all, without charging me like a hour for labor.
 
#36 ·
Just started the work...

So far we found there are some shavings of tiny metal pieces in the pan - I'm assuming that's not good. It wasn't full of shavings but just a little bit.

I'm going to continue to do the work and make the changes but just wanted to see what you guys thought about this.

Thanks,
Jay
 
#37 · (Edited)
Well, bad signs.

We've dropped the pan and there is some cloudyness to the fluid. Not much but some. There is also some metal flake.

The worst is yet to come though. There is no magnet in the pan and there is no ATF filter. I recently (within the past 3 months) had this transmission serviced at the local dealership where they supposedly replaced the fluid and the filter. I'm pissed as hell. Unfortunately, I don't have a replacement magnet so I'm going to have to put it back together with just the filter for now.

And even worse. The fluid is obviously quite old. It's very very dark, not like it should be at all after only 3 months. Apparently the dealership did absolutely nothing.
 
#42 ·
...And even worse. The fluid is obviously quite old. It's very very dark, not like it should be at all after only 3 months. Apparently the dealership did absolutely nothing.
Did they supposedly change all the fluid or only part of it? If they only drained the pan, that removes about 30% so could explain why it looks as dark as it does. However, there is no excuse for them not replacing the filter and the pan magnet!

<edit> Sorry, just saw your update. Glad to hear the filter was there after all.
 
#39 · (Edited)
The great thing is that the invoice from the dealer has a new filter right on it. That and new fluid and new bushings and new everything. It is totally clear that they didn't do anything

I did manager to get another 4 quarts of ATF so now we have 8 for the job. We are going to clean out the pan as best we can, drain the torque converter and put all 8 quarts in. With that, a new spring, a new conductor plate and actually HAVING a filter hopefully this tranny will behave better.

Very sad day. I don't even know where to begin trying to confront the dealer with this. We are taking pictures and some movies of everything we find though, so at least I have some documentation.

The one thing I don't have is the magnet and there is no way I can source one this weekend. For now I'm just going to have to put it back together without one and hope everything works out ok.

Also, the shaving are quite quite small. Maybe 1/64th of an inch or less, so really itty bitty. Not sure what a lot of shavings or a little shavings is in this case, but it didn't seem to me that the fluid was like swimming in them or anything.
 
#40 ·
Some people have written that most of the bits of the transmission found in the pan are non-ferrous and therefore non-magnetic anyway so the pan magnet is of questionable value. Irrespective of that, I'd be much more confortable having one.
 
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