Hi all, we purchased a 2017 GLC43 about 2 months ago and always noticed a weird down shifting. The shifting up was jerky but not as bad as the down shifts. Shifts are as if it hold on to the gears for too long and high pressure so when it downshifts it very jerky.

First thing I thought was probably time for transmission service because it was already at 78K miles. The car has been dealer maintained but I could not tell if that was done. But it did not help very much with the shifting.

Then I found a video on resetting the adaptive transmission and doing it manually holding down the gas pedal. It helped a little bit but not as significant as I thought.

Next was I got a message about stop vehicle and let vehicle run. At this point I checked the battery and its a Mercedes AGM from 2020. I figure it was okay and maybe just low voltage but doing this several times I decided it was a good time to go ahead and buy a new battery. This is odd to me because my other Mercedes batteries will last 5-6 years. I have one that is 10 years old and no issues. So I bought a AGM battery from Walmart and used my scanner to reset BCM and reset transmission adaption.

At this moment the car shifts like a normal Mercedes for the most part. Very little jerkiness that was annoying and for passengers they thought the car was falling apart which is embarrassing.

I figure this might be helpful to some regardless of car type to look into the battery as a potential issue of shifting oddities.

 

Good trial and error steps, what scanner did you use and did you check the aux battery?

 

Yes, most likely it's time for trany service.
See my post, there is whole section for
Problems related to shifting up or down and P and N. Process takes about 15 mins and trany does a lot of clicks and you keep gas pedal to the floor (engine stays at low RPM )

https://mbworld.org/forums/glc-class...problem-6.html

 

The valve body in the transmission can become contaminated and potentially cause similar symptoms without triggering failure indicators. Have an experienced MB transmission service provider road test and evaluate. There shouldn’t be a charge for that.
My 2018 developed troubles at 52K. I had the entire transmission replaced under warranty. If you don’t have existing warranty coverage you might want to just have the transmission serviced and see if the issues are resolved.

 

Thanks DanD, so just use Xentry to do this transmission reset? I have Xentry but have been using my Xtool.

Thanks,

Andrew

 

You can try it, but I think it's time for a service.

 

If you have XENTRY, recommend doing the standstill adaptation, I do too recommend doing the transmission fluid.

 

Thanks DanD and W205C43PFL,

I've got the fluids changed and the filter changed on the trans. Have done the trans adaption learning on the Xtool D8. Will do another fluid/filter change and do the xentry reset.

Thanks,

Andrew

 

Did you drain the fluid from the torque converter?

You'll need to use Xentry to properly bleed the valves and check the transmission oil level. There are two steps: one with the engine off and one with the engine on. I'm not sure if any other tool can perform this.

 

Sounds good : ) Appreciate the update and good to hear things are going smooth, also curious as well if you drained the torque converter.

 

Thanks all for getting back with me. I did not get to drain the torque converter. I will look up the process and get it done. Any pointers on how best to do this? I had a local shop do the trans drain and fill with filter.

Thanks,

Andrew

 

You need to do it at the same time as they are connected. Please see the discussion I mention above. I have all work instructions posted there and there is a lot of good information how to do it.

 

That's a good question, someone did this on a sedan using a Launch CReader scanner tool thing, not sure if they were able to drain the torque converter with it: https://mbworld.org/forums/c450-c43-...e-success.html

 

No tool is needed to drain the torque converter.

The hardest part is lining up the torque converter drain plug with the hole in the car's frame when doing it by yourself. You have to turn the engine, get under the car to check, and it might take a few tries to get it aligned.

 

Thanks for confirming, I thought there was a XENTRY step to be performed before doing the torque converter drain hence why I was curious is that Launch CReader scanner tool has the same step programmed to be performed just like XENTRY.