Mercedes w166 Without changing gears warning

[Mosman40]

Hello Everyone,

Need some help. I had a message come up on my ML350 2012. "wintout changing gears consult workshop". I was diring on the motorway, so just continued to drive until I got home. Nex day the message was gone, so drove to work and car was fine. When I got home in the evening just as I was about to park, the car went into neutral and would not get into any gears. Switched the car off and phoned mobilio. They sent RAC the next day as it was not priority. RAC man started the car and everything was fine car was getting into gears no issue. So he asked me to drive it to Mercedes and he followed me behind just to make sure I get there. Dropped it off yesterday at Mercedes, it was also due for service with them tomorrow. Today I get a service message to say service has been done, but nothing on the transmission issue, so I phoned them, and they told me that the transmission just needed software update on one of the ECUs. I'm a little sceptical that a software update would resolve this. The car was driving fine, so why would a new software fix an issue, if the old software was driving the car just fine until recent, nothing else has changed. I hope I'm making sense of this.

I'm yet to pick up the car as they found that both rear springs were broken and quoted me £360 to replace. I agreed to get these replaced but it means another day for the car to be with them, which I don't mind.

My issue is the transmission, does a software update really fix such an issue. I also have to pay £180 for diagnostic, as they told me this when I took the car in, so if it's a software update, I'm hoping they don't charge me for the diagnostic, wishful thinking.

Has anyone ever had this issue and software update fixed it?

Thanks

 

[Mosman40]

Just an update, so the issue is back again even after the software update. It would seem that when I drive local it's fine, however when I drive the car on the motorway for an hour or so, this is when the error come through. I can continue to drive, however once I stop and turn the car off, it would go into neutral and would not go into park or reverse. I can still shift into drive but not park. Once turned off would not start again as it's stuck in neutral. Funny bit is if I leave the car off for 5 to 10 mins, then the car would shift into park and I can start and shifts normal for a few mins, then again the error would show up. I have connected with Autel scanner and cleared the codes and works ok for local but as soon as I have driven for an hour or so the error come back.

I looked through the forums and replaced the 30amp Maxi Blade fuse in the engine compartment. I haven't tested it on the motorway since so not sure if this solved the problem. When I removed the old fuse, it looked ok so not sure. Will see.

Any advise would be helpful if anyone has seen this issue before and how to resolve it.

MB are giving me an appointment of around 2 months from now so can't wait that long.

 

[Mosman40]

Just a quick update. I'm getting the car recovered to MB dealer today for them to sort out this problem. I had MB tech come out and they scanned the car and have advised to drive it into MB dealer. The codes are related to the ISM. The problem has gotten worsts and on the weekend the error came up 3 times while driving so just drove home and left the car on the drive way. When the MB tech showed up the next days the car had cooed down and was able to start and change gears. The error codes were still there, so he did not clear them but asked me to limp to MB dealer this Monday morning and let them sort it out.

I hope they can find the issue and get it resolved quickly. It's really frustrating. Will update once MB have had a look, hopefully they will not turn me away as the MB Tech asked me not to even phone them but just show up.

 

[ALFAitalia]

Most dealers rarely have the spare capacity to accept an unbooked appointment.... so hopefully they are not too busy and will squeeze you in.

 

[Mosman40]

Most dealers rarely have the spare capacity to accept an unbooked appointment.... so hopefully they are not too busy and will squeeze you in.

Hi Alfaitalia,

Just back from the MB dealers and they have agreed to book me in and have a look at the car. They even gave me a courtesy car, so hopefully they can get this resolved quickly. Since I have a courtesy car from them, I'm hoping this will motivate them to get this resolved quickly.

I will update once I hear back from them as to the problem.

 

[ALFAitalia]

Result!!!

 

[Mosman40]

Just a quick update. Heard from Mercedes dealer yesterday and they have diagnosed that it's the ISM that needs replacing plus some hose. Total they have quoted me for the job is around £800 for the parts and labour. This does not include the diagnostics as I paid for the last time I took it in for the same issue, so not paying twice.

The jobs should hopefully take a few days and I should have the car back by early next week. Fingers crossed this fixes the issue. Currently I have a courtesy 2024 model Cla Class Phev 250 Amg Line Executive, so don't mind the wait.

 

[Mosman40]

UPDATE - Just picked up my car today as I was away on holiday and had to keep the loan car until I came back. Went to Mercedes today to pick up my car and it's all done. They replaced the switching unit, which I take it is the ISM. Car drive a little jerky as the gears are changing but I take it it's in learning mode due to the new ISM. Hopefully this should improve.
Total cost for replacing the switching unit and a 2 hoses came to £777.60. This excludes the diagnostic as I paid for this last time so they did not charge me this time. Switching unit is £414+225 labour+20% VAT. Hopefully this should now resolve the issue but won't know until I have driven it for an hour or so. If the issue comes back I will update, otherwise it will mean it's fixed.

@ALFAitalia Thanks