enjayjay

Hi Guys, first post - looking for advice.

My wife GLC won't go into park sometimes. If you switch engine off first then press park button on stalk it will, and happily switch back and forth P <->N etc then - so its not the button.
It will also go into park fine if you just open the door while running so again not something with transmission not able to. Seems to me its not the stalk/button or drink spill related like the centre console based changers.

Must be a sensor telling car something wrong?

Anyone experienced same or got any tips? 2015 GLC250d

Thanks, Nick

abacnus

It sounds pretty odd, I do not know, but just curious. It cannot put into park when the car is fully stop?

Btw, 2015 GLC is like the very first year of GLC.

abacnus

It seems common issue though. FYI: https://medium.com/@casperbradley/wh...k-efbd2c3498e7

decorily

You give us specific circumstances in which it will function properly. ...can you tell us under what circumstances it doesn't function properly.
Does the central display show the 'options ' available in terms of shifting?

enjayjay

It has always worked as normal and as expected- if the car is stopped with foot brakes on you press the button for park and it goes into park.

Just sometimes now - at full stop with foot brake on - won’t go into park with button - does nothing with no message.

but as explained before - open the driver door it immediately will. Or turn engine off first and then park button works.

I’m not sure what you mean by options on central display - the MFD shows what gear you’re in is all.

yes this was a pre ordered first delivery car - one of the first in Australia.

enjayjay

thanks but none of those are relevant I think - it goes into park fine when you open the door or switch off engine first - it doesn’t seem mechanical in the transmission or the switch.

decorily

[QUOTE=enjayjay;8221768]

I’m not sure what you mean by options on central display - the MFD shows what gear you’re in is all.
/QUOTE]

In the MFD beside the symbol to show which gear you are in D, R etc there are little triangular symbols which show which options are available.
For instance if P is selected the symbols should show D and R as selectable options.
For example if in D and you start to move N will stay highlighted as an option but R will not.

dmegeath

Don't mean to sound like a wise guy, but any chance you are not depressing the brake pedal when you switch to Park?

enjayjay

[QUOTE=decorily;8221823]so yes it shows the options as you describe when the problem is happening - just as normal. I did some more playing as it just happened now. 2 other things won’t work - distronic and hill hold.

distrinic just says it’s unavailable. And hill hold nothing happens when you double push brake peddle. I’m leaning towards brake sensor. Soon as I reboot car then they all work again.

enjayjay

na mate. Brake is on. Even tried slamming it hard to the floor. As per other update today - hill hold won’t work nor distronic then this is happening either. Turn car off and on again then all works.

decorily

Time to scan for fault codes!

abacnus

What is hill hold? Is that brake hold?

For mine, it is to press down the brake pedal harder to activate brake hold instead of double press though.

GateKeeper

If you are on an incline don’t remember that exact angle or degree you have to be on, and you stop, the vehicle will hold the brakes on for a few seconds to prevent the car from rolling backward or forward giving you time to hit the gas and go.

great for coming out of underground parking lots and there is a lineup to get out and you happen to get stuck waiting before you can fully get out, and someone is behind you, this way you don’t roll into them

.

enjayjay

Yeah same same - kind of push harder or push again I guess. Then shows hold on the screen. So that doesn't work when the issue is happening.

decorily

No...
Hill hold and brake hold are two different functions.

Hill hold stops the car rolling backwards when the brake pedal is released and should activate automatically.
Brake hold stops the car starting to move forward when the brake pedal is released and needs to be activated by depressing the brake pedal 'firmly' past the normal stopping point.

enjayjay

Well if you are worried about naming - what you are talking about is called "Hill start assist" - I am talking about brake hold as explained in previous - I use it on non flat ground to hold brake on hence calling it hill hold but yes brake hold is probably merc naming.

decorily

Not worried about naming at all....just trying to be helpful!

You said both were "same"....they aren't!
Anyway I'm afraid I can't help with your issue but hopefully you get a solution.

GateKeeper

Hill start assist , will not show HOLD on the dash

so they are different

​​​​​​.

abacnus

So how often do you use such brake hold? And how quick to double push?

I am just guessing here, would it be possible that some sensor is confused as the brake pedal is pushing too much and too quick when double tapping (like double tap on the mouse is too quick). It is supposed to just push harder after stop in order to hold the brake.

enjayjay

Na mate - this all normally works fine, it just doesn't work when the other two issues are present.
a) the car won't go into park - this is the issue we first noticed
b) distronic will say unavailable - you will know that the car will not be able to go into park later if you get this while driving while trying to turn it on
c) brake hold won't function - I found this through testing for other things that dont work when I had the above issues - they all happen together if they happen at all



I presume a brake sensor is the problem as it would be used for all 3 functions I imagine - but I need to scan for codes or take it to the dealer. It doesn't happen all the time - just occasionally and its my wifes car so my opportunity for testing when the issue is happening is limited!

Pinspector

OK: I have a 2018 GLC300. On several occasions, I've stopped, pushed the PARK button and stopped the engine. Gathering my stuff from the front seat and letting my foot off the brake, I find the car drifting either forward or backward (depending on the incline). Brought this to the attention of MB during the warranty. They replaced the trans stalk on the column and did a trans software update. Still waiting to see if this fixed it or not. Here's the other issue: I had a 2021 GLC300 loaner when in the shop last. I tried this: Stop the car, push the Off button on the starter. Vehicle automatically shifts to PARK. NOTE: Wife's car is an Audi and I had a loaner from them also recently. 2021 Audi Q5 also shifts automatically into PARK when ignition is shut off. Mother-in-Law's 2019 Lincoln MKZ does the same thing: Park the car, shut the engine off and it automatically goes to PARK. Sounds like a software issue, no? I asked my local MB service center if they can do a software update to have my 2018 GLC300 automatically shift to PARK when the engine is turned off. Apparently they looked at me like I had 3 eyes!
Please, have any of you had a similar issue and is there a technical bulletin that will fix this issue?

enjayjay

This sounds very similar to mine - when you are used to not checking the display this is exactly what I do - press the park button without looking, turn off engine and take foot off brake - then it rolls (when my fault is happening). They have diagnosed the fix the same as yours - replace the transmission selector module - ($1900!!!) as it was reporting "improbable data" - waiting on part still.

I have seen in another forum that people claim that early GLCs like mine do not put in park when engine is turned off (mine is the same as yours), but newer ones do go into park automatically as you describe. I'll be interested to see if there is a way to have a software update to do that too.

Pinspector

I'm not an automotive or MB engineer, I just think this has to be a simple software issue. I've reached out to the service manager at local MB dealer and asked him to see what he knows. He's been really great in the past. Will monitor the condition. Still under warranty until July 2021.

rimutakaman

My wife's 2017 GLC experienced the same issue last night -- she drove 5 miles, came to a stop in a parking lot, and it would not go into park. Opening the door did not correct the issue. Turning the vehicle off/on did correct the issue. I am just going to follow this thread in case someone finds and posts the solution.

enjayjay

fix for us was replacing the transmission selector module at great expense. Seems many generations of Mercs are known for this kind of thing too.