ericmb

The transmission was harsh(shfting sometimes eratically) so I took the car to the dealer. I remembered to turn the vario roof module off before giving it to the dealer. It took them a long time and they finally said that something is draining the power. They probed and found the vario roof module. Now they are saying that the transmission issue was caused by this and that it is not covered by the warranty(thousands of dollars so far!). The car is still in the shop and I have told them to remove the vario module and test the transmission afterwards. They said they will need to do the adptations. The scary thing is that I took the car in once before for the same issue, they said that the transmission fluid was low and they did the adaptations after refilling it and told me that every thing was fine! Now I am very suspicious that they are going to to the same thing and put the blame on the vario module and all the cost on me. When I ask them how it can cause transmission problem, they give me a convoluted answer of how the car is all computerized and so on.
I guess the big questions is:" Can the vario roof module cause a trasnsmission problem?"

DansSlk

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OK mate lets take this from the top,

The transmission was shifting harshly now on an auto box this is normally caused by one of the following reasons, a hardware defect in the gearbox itself, a fault in the electro-hydraulic control module, fault in the shifter module, the ECU or a situation where the fluid level has dropped.

I am not aware of a situation where a low battery caused from power drain has had adverse effects on the shifting of the transmission unless it gets to the state where the engine cant start, normally all that happens is the shifter module locks the shifter into P blocking the tranny.

In the 7G there was a valve body fault that would cause harsh shifting between the first few gears this should have been one of the first things checked, also if you have a fluid leak as the level drops shifts between all gears will become harsh and the adaptions will also tend to move out of an acceptable range to try and compensate for that, it sounds to me like you have the second fault because they re-filled and reset before and it was all fine for a while now technically this is a transmission fault and the law says they are liable to fix it but they can very easy change that to have you foot the bill unfortunately thats a fact of life they get paid more form you than they do from MB so it pays for them to blame you.

It is true that the car is totally computerized and all the components are networked so to answer your question yes a vario roof module can effect the cars transmission system but the roof module is on CAN-B and the tranny on CAN-C these two networks are connected by what we call the ZGW "Central Gateway" this looks for messages on both networks that should be copied onto the other and when it finds them it does exactly that thing is there are no roof control messages that should be on the CAN-C BUS at all so to have a situation where a faulty module is effecting your tranny is highly unlikely.

The first type of roof module before the smarttop units came onto the market did cause a large power drain so they are not BS'ing you with that statement but for it to be effecting the tranny so much as to cause bad shifts you would not be able to start the engine the power would be so low.

I think there is a 99.5% chance this is a fault with the tranny itself and .5% any other component but the dealer does not need to justify themselves like that so my advice to you would be go to a different dealership explain the situation have them look over the car check it for faults, leaks and so on and then tell you what they think they are more likely to help out since they will be gaining a customer.

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mtiede

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And maybe remove the module before going to the new dealer

Addicted2Speed

Remove the module and go to a different dealer if they are giving you BS about it... there is no way that the module can cause this probem. Typical stealership tactics, I'm not surprised at all.

DansSlk

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mtiede, I see where your coming from but the module is a vital piece of all this he is going to have to explain it to them to get his story across properly, I don't think it would be too much of a problem the second dealer has no need to go along with the diagnosis provided by the first one they don't get anything from it and if they are on the level with ericmb then they stand to gain a customer.

Addicted2Speed, Don't mean to be argumentative but thats simply not true the man asked can it cause the problem the answer is yes every single module is connected to each other these two units are on different but connected networks the central gateway should stop the transfer of errand signals between them but that is not guaranteed it was not designed to do that, its is highly unlikely that the module is the cause of this because to cause any harm it would need to somehow malfunction and produce signals that the gateway accepts as needing to be copied over and that the TCU accepts as valid and acts on them thats next to impossible but not completely out of the window. Gotta understand the complexity of these thing's everything is computer controlled in this case i think the dealer/MB should pay for it but it does highlight the fact that people need to accept responsibility if they mod the cars MB can't be expected to pay for everything.

Not having a pop at you ericmb as i said above and in my first post the dealer should pay for this one not you i was just trying to highlight the risks involved with everything these days.

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ericmb

Hi Guys. Thanks for the replies. The problem is that the car is still in the dealership(close to 3 weeks now!) and I can't take it to any other places/dealership to show until they are done with the car. I went down to the dealership twice while they were working on the car. Once they showeed me the module and how it drops the Amp when it is connected. I told them it doesn't make sense that b/c of that the transmission would get into problem, that there are many other R171ers using them with no problem and that I contacted the manufacturer and he said it shouldn't cause transmission problem and that has never been reported. The deal was to remove the module and see if the transmission works propperly, after adaptations. First of all, I was worried that like the other times, they would say transmission is fine after an adaptation although it got into trouble agian shortly, but I had no other choice and I agreed. It's been a week now that they are re-assembling the car "to a condition that is drivable" and no news yet(well, I went down there after 2 days from the first visit and they hadn't touched it yet, they claimed the got very busy!) I just don't trust the dealer anymore and I don't know what they are doing with the car, but on the other hand for the time-being I don't see a lot of options until I get the car back.

dsb

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I wish you the best of luck. I've had mine installed for quite some time now. I've been to the dealership 3 times since and forgot to disable it everytime. Luckily, they haven't blamed or mentioned it for any issues. I guess I should really start removing it especially if there's ever an issue.

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Addicted2Speed

I see what you're saying DansSLK. I assumed that it wasnt the module because so many members on this forum have it and we would've probably heard about the problem much earlier. It is strange that only this SLK seems to be affected by it. If its theoretically possible though, I guess I'm not going to buy one anymore before the situation is cleared up....

DansSlk

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I agree mate if it was the module at fault i am sure we would have seen more issues with this, i am just thinking a malfunctioning module that could maybe have been damaged via a voltage spike or such like could be transmitting errand signals something that could be a one off but like i say thats extremely unlikely, it does sound like the dealer has seen a weakness and pounced on it but without actually seeing DAS printouts of the errors and stuff its impossible to rule anything out.

I am not 100% but i think this could be one of the Piecha modules i.e the first one to be released before SmartTop apart from the issue with option 5 the new modules have been practically faultless so i would not let this bother you if you want one go for it!

Hope my post did not sound like a rant mate it was not meant like that at all.

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DansSlk

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As i said in the other posts i think you have one of the Piecha units correct? they did cause quite a lot of voltage drain on the car and low voltage faults have been traced to them before.

But for voltage to effect your transmission it would need to be so low there is no chance of even getting the engine to turn over no matter fire.

It does sound like other's have said the dealer is taking advantage but its not possible to say that for sure, i suggest you go down there and put pressure on them give them a deadline and tell them the car will be ready or there will be a truck coming to pick it up and they will foot the bill or they can speak to your lawyer that scares the hell outta them and will hurry them up no end.

To assemble a totally stripped car to totally complete take 4/5 days total to fill the transmission and put the panels back together can be done in hours. They are making the setting of adaptions sound very complex but in reality its just a matter of hooking the car up to the computer and going for a spin (a short one at that).

I think you have a transmission leak or a damaged valve that is causing a low fluid level and giving you the crappy shifts

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mcat

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huh! This is the first I have heard of any problems with the Piecha unit and there is a an awful lot of them out there.

Are you saying I should remove mine? I did have a flat battery after I didn't use my car for 4 weeks. Would the Piecha module be the cause of this or would it have happened anyway?

DansSlk

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Its not a case of bad modules as such its that they require more power on standby than the rest of the modules in the car.

That means they do drain the cars battery faster when they are connected and people have mentioned it when talking about dead batteries.

Its not like without it connected your battery will last a month and with it connected it will last a week we are talking maybe a day or two at the most, but it does have an effect.

A flat after 4 weeks is something i would expect to be honest, a few weeks tops outta these batteries most of the time even less in the UK climate

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Ynot

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This is the first I've heard of any problems besides drainging of the battery (1st gen piecha roof module).

I would not remove it if you are taken it for a basic service, (oil and filter change) but if you have a SRS error, or any engine light warning, I would take it out just as a precaution, this is a prime example, the stealer will use any excuse to blame you.

The 1st generation Piecha roof module will drain you battery in two weeks, if I know I'm going to park it for 2 weeks or more, I hook it up to a battery tender. When I didn't have it installed, I remember I had it parked for two months w/o a problem. I would not let this incident stop me from enjoying the roof module.

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