I want to clarify some simple facts before I move ahead.
I cannot find a S500 in the service manual. There is an S550. What is the model of your car? I do not have the manual link for the S500 if it is not a typo.
I can look at models with the same transmission as the trouble codes and symptoms will be the same, it is the configuration that I really need.
Is the car an automatic or manual transmission? I have been assuming automatic.
Is the car rear wheel drive? I have assumed so as you referred to the differential oil as being different from the transmission oil. In a front wheel drive car the transmission oil is the differential lubricant.
I am also assuming it is an automatic transmission because they tried to re-program the computer to make it work.
Also the A80 code means not much more than a part is not working correctly.
However, in regards to the symptoms, services and the things you have told me about the outcome, I can tell you this despite knowing the exact model of your car as long as it is an automatic transmission.
Your car has a lot of miles on it. Your tansmission lubricant should be chagnged every 60,000 miles. If it is not, wear and tear would get the clutch packes at around the mileage you have if not sooner. If the fluid had not been changed regularly or even if it did, the metal in the oil is not surprising. I would expect it to happen more often when the fluid is not changed though. This is definately an indication that the transmission needs repair. The fact that it does not go into reverse could be the result of clutch and metal particles clogging up ports that control shifting. This is either a solenoid or a oil circuit in the valve body. The shuddering you feel is happening when you shift or at all times? If it when you shift, the torque converter or torque converter clutch is bad. If it happens all the time, the transmission has a much worse issue that is probably a bad bearing or bushing.
I do not know if you went to a dealership or not. If you wnent to a dealership I would feel better about the fact that the transmission computer or the ECU was re-programmed. This is really tough to do without special tools and circuit flash components that would be specific to the Mercedes. Unless there was a service bulletin put out about the programming that controls the transmission, re-programming it would be risky unless the technician really knew what he was doing. But, don't let that overshadow the problem. I bring it up so you can check on the service bulletin. You can go to a delearship and the service department can tell you if there is a service bulletin in regards to the cars computer programming being updated. Sevice bulletins are available to the public upon request.
In the end, the transmission does need to be fully rebuilt. If the computer was programmed and it is not the proper firmware for the transmission or there was no update issued by Mercedes that you can find in a service bulletin, I would make sure that it is set to the programming that is supposed to be at.
If it is not the proper firmware and the transmission is rebuilt it could damage the transmkission and any warranty would be void.
I cannot say that the shop is wrong or right at this point as they are so many variables and things change really fast when a transmission ends up being in such bad shape. However, if the problem got worse after the computer program, that might have caused more problems for you.
So, I am a little skeptical of the repair shop. I would go online and maybe even Angies list or the better business bureau or even check the yellow pages for reviews on there service. If they have any complaints at all, I would take the car elsewhere. Other things to look at in a repair shop that is good are things like how clean it is kept, how modern the diagnostic tools are and the overall professionalism of the staff. Does the staff wear a uniform or blue jeans and a t-shirt? These simple things can be signs of a shop that is not run profesionaly.
I realize that you will lose the money you have invest in the car at that repair shop, but you will lose much more if they repair it and do not do it properly.
Finding a repair shop that re-flashes computers will not be easy. You will have to go to a dealership or find a place that has the equipment to do it. There is a shop that I have worked with, it was on an Acura though, that does re-flash computers. It is on-line and they may be able to re-flash the computer to its proper settings. It is called, "The Swap Shop" and can be found at; theswapwhop. Com.
You are in a situation that is really tough and you are going to have to think about the long term results. You should ask them, after looking for a service bulletin, why and how they re-programmed the computer and with what model of car did they re-flash it with. Access the shop and go with your instinct as whether to have them repair it or not. Get another opinion if you can.
At this point rebuilding the transmission is something that must be done. You must make sure that the computer has the right programming o ensure the transmission will not be damaged.
Let me know if you have any questions as I know this is complicated.
I will respond ASAP.
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Saturday, January 21st, 2012 AT 11:38 PM