2003 SL500 Computer Problem (coolant, ESP, check engine, transmission)
Since what turns out to be slightly before my warrantee ran out I have been experiencing what appears to be a computer problem.
It started innocently enough over a year ago by having the coolant warning come on momentarily after a 400-mile long road trip. At the same time as the warning the needle on the coolant gauge dropped to zero and quickly returned to normal. I reported this problem to MB but it was never resolved and I did not see the coolant warning for a long time.
However, I did experience some occasional complaints about the ESP with a "visit workshop" warning. This was after the warrantee ran out so I never followed up on it. I received this warning a few times but went several weeks without seeing any problems.
Then it gets worse. While driving I get the coolant problem, the ESP problem and now a check engine and a "Transmission" warning at roughly the same time. When this occurred the car remained in either 1st or 2nd gear. This is presumably the "limp mode" I saw referenced in the owners manual.
I quickly pulled over and shut the car off in an attempt to reset the computer and get me home. However, the car failed to start after this event until I had the key removed for several minutes and gave it one more try. I was then error free and I made it home. I never had another problem for several weeks.
Today I had the same bad sequence occur except the problem cleared after shutting off the car for a couple of minutes.
I have another problem where my car will not start after it has been off for hours. The key simply has no effect. Lights in the center console will blink in some kind of pattern. This could be just the key battery but I have not confirmed that.
I am quite confident that there is not any real problem except for the computer telling me there are problems.
Has anyone experienced this issue?
What is required to fix it?
you need to have a short test ran by the dealer or someone with a DAS. this is the only way to begin diagnosis. the last car i had that had similiar issues was a CLS500 and it ended up have a water leak that damaged a control unit under the carpet. not saying thats your issue, but a short test will point you in some direction.
I actually disconnected and reconnected the battery in an effort to get the car restarted quicker after the last event. It did start right away but then had a new message of "ESP disabled". The warning existed only for that start and every trip after that has been fine.
I still have what an issue what seemed to be an overnight degrading of suspension (started months ago) which may be a blown strut. Cruise control does not work over 60mph. This may be due to aftermarket or out of balance wheels since it is behaving exactly as it did when I once used a loaner mismatched wheel on the front drivers side.
Anyway, I will take it in. I just wanted to make sure this was not a commmon issue.
Car has been running perfect since the last battery disconnect. I thought high humidity had something to do with the problem but it has been pretty wet here lately and still good.
Problem with cruise control was due to low air pressure in the front left tire. Past problems were due to loaner wheel on front left side. Seems that the cruise control is sensitive to changes to the front left side. Hmmm.
The problems actually still exist an reoccur perhaps every three months. Seeing as though the problem originally ocurred under warranty (and I did report it then as a glitch in the coolant gauge) I am wondering if I will be able to get this fixed for free as it should have been in the first place. I suppose I should be kicking myself for not taking it in sooner but the problem happens so infrequently and I keep getting false hope that it has gone away. Anyway, I can not risk it anymore as the last time it acted up the computer kept me in first gear as I was trying to accelerate quickly and then clanked hard as it eventually shifted gears.
It did not help that I spent some time fighting MB a little bit over the gas tank incident and was hesitent to go back in immediately to report yet another reoccuring problem that I originally reported under warranty.
The problems actually still exist an reoccur perhaps every three months. Seeing as though the problem originally ocurred under warranty (and I did report it then as a glitch in the coolant gauge) I am wondering if I will be able to get this fixed for free as it should have been in the first place. I suppose I should be kicking myself for not taking it in sooner but the problem happens so infrequently and I keep getting false hope that it has gone away. Anyway, I can not risk it anymore as the last time it acted up the computer kept me in first gear as I was trying to accelerate quickly and then clanked hard as it eventually shifted gears.
It did not help that I spent some time fighting MB a little bit over the gas tank incident and was hesitent to go back in immediately to report yet another reoccuring problem that I originally reported under warranty.
Its going to be difficult to convince the dealer to warranty the issue mostly because its not just the one issue but many now.. e.g. if you go complaining about all the listed issues they will say that you never complained about any issues but the coolant light/gauge issue. As far as getting that warrantied you can always try... MB corporate will have to approve it and they typically dont unless the problem is well documented and common to a particular model.
Now on to your particular problem... It could be a problem with the vehicle network.. That will cause these sorts of issues.. It could be a problem with a few different modules; for instance the front SAM is where all the underhood sensors connect and their signals go over the network from there.. if the SAM goes bad it will cause these problems. It could be a battery/power problem. A low battery or a loose cable will cause modules to shut down or malfunction. Its just too difficult to diagnose without the dealer computer. Take it to MB service and have them check the event log.. the car remembers any faults that you have and this will provide a good idea of what is happening.
i have the same problem on my C320 last week. the coolant warning, ESP, and check engine lights suddenly came out and flashes. since then, these errors keep coming out from time to time. have you got these problems fixed yet? did the dealer tell you what's wrong?
My car has been at the dealer for almost three weeks (this is in addition to a week it spent there a month or so ago). After a week and a half they gave up trying to reproduce my issue and told me to come get my car. Fortunately for me it failed to start when I went to leave. They were able to hook up the computer while the car was in the failing state. This was certainly lucky for me that they were able to confirm an issue. Apparently they were still unable to get the necessary information an have spent another week and a half trying to get it to fail again. I probably will not have a starter left by the time they get done.
A few months ago I was told the cause of the problem was a depleted rear (control system)battery. I ended up paying over 300.00 for a 120.00 battery (Pep Boys) and it did not fix the problem.
Still, as a computer engineer, I can recognize a likely computer (or network) issues and realize these can be difficult to pinpoint. The fault here is really with the Engineers that designed the diagnostics system and failed to close off this point of failure. This includes the network issues. Without this being done during the design, it will render the mechanics helpless. I was told that for whatever reason the error codes were not even being stored after the failure.
It is funny how I am more comfortable getting into the loaner car than I had the SL. My wife will actually drive the C class since she is not afraid of getting stranded somewhere.
Frank/Rob,
Sorry I did not respond sooner. I did not get an email for some reason. Glad to see I am no longer talking to myself on this one.
Sure sounds like the same issue. Let me know if you had this resolved. You may want to wait till I get done an answer. Still, it might take a year or more to really know if it is fixed.
The dealer first suspected the communication link as being the problem but seeing as though they still have my car then it is impossible to say if this is accurate.
I do not think it is the communication link itself based upon the circumstances in which the first error occurred. After a long summer road trip during mid day from Tucson AZ (105F+ and dry) to the southern California coast the car suddenly had a glitch just about the time I hit the colder wet air at the beach. I do not think this was a coincidence and it leads me to believe that maybe condensation developed somewhere it should not have. I must say that I am not familiar with the design of the communication link in the car but I certainly can see how this could be the source also. I am just putting my money on one of the main modules.
Is there a main control computer in the car? Does the before-mentioned C320 have the same computer system for the most part?
2003 SL500 Computer Problem (coolant, ESP, check engine, transmission) 
Linear Mode
