Auto gear lever unit issue C250 2012

[Adywheels]

Hello All

Got a strange issue that I think is the gear selector unit, below my symptoms & fault codes.

My main question is.... If it is the selector unit can I just buy a 2nd hand one and swap it out or does it need Coding in, i cant seem to find this specific answer about the coding so i'm hoping it could be a straight swap out?

C250 CGi 1.8T petrol
7 Sp Tiptronic Auto
2012 model

Selector lever part number - A204 267 7524

Stuck in Park.
Pressing Yellow button allows gear selection as normal.
Once out of Park the car drives through gears correctly.
Seems to have a bit of a snatch/jolt between Gear 1&2 at about 10mph.
After driving if put back into Park, you need to press yellow button again to select gears.
Dashboard display shows correct gears selected as you drive.
Tiptronic paddles work correctly in Drive (once out of park).
S-M-E button next to gear lever is unresponsive does nothing when pressed.
Car in E mode all the time, cant select S - M.

2 Fault codes (from iCarsoft CR Max Diagnostic) as follows….
U010100 – Communication with Control unit “Transmission” Has a Malfunction.
C103 – No CAN Message was received from control unit N15/5 (Electronic Selector Lever Module Control Unit).

Thanks in advance for an advice on this headache

 

[Adywheels]

Found the issue.... Unbelievable really how simple! Just a 5amp fuse in the under the bonnet fuse box had blown, i visually checked this fuse and it 'looked' OK but it had actually blown just under the thicker plastic bit so was impossible to see the hair line break, using a multimeter was how i discovered it. All fixed now.

But now i have a load rumble noise in 6th and 7th gear, i thought it was a rear wheel bearing but gears 1-5 are quite as soon as i get into 6th on a motorway the noise starts and 7th is worse ... NO idea

 

[AlanGunn]

Has the auto box been serviced at all.

 

[Adywheels]

Has the auto box been serviced at all.

Hi Alan, thanks for replying

I'm not sure when it was last serviced TBH i have no paperwork for it, the car has done a lot of miles 170,000 !!

I was planning to do an gearbox oil and filter service on it in the near future...... But then this noise started after a 2 hour motorway drive the other day and now it happens anytime i get to like 65mph and above where the car goes into 6th & 7th. If i use the paddle shifts and drop it into 5th the noise goes away even at 70mph, so i really think it is an internal issue with those gears, I hope a full oil service will help ??

It changes gear and drives smoothly in all gears except for this loud rumbling bearing noise in 6th & 7th which i can also feel through the gear shifter.

I got under it today and there are no visible leaks i also removed & checked the rear gearbox engine mount which is fine so i doubt its a mounting vibration like forum posts have said who had this issue. I've seen it is the deeper new style sump with the larger oval divets, so blue oil and filter are required, which i will get from Merc this week and do a change.

Love this car but it is killing me right now, Ive just done the cam phasers, new alternator, new battery, new disc & pads all round, diff oil, gear selector issue & currently searching for the engine oil leaks from every gasket it seems.....

 

[Adywheels]

Hi Alan, thanks for replying

I'm not sure when it was last serviced TBH i have no paperwork for it, the car has done a lot of miles 170,000 !!

I was planning to do an gearbox oil and filter service on it in the near future...... But then this noise started after a 2 hour motorway drive the other day and now it happens anytime i get to like 65mph and above where the car goes into 6th & 7th. If i use the paddle shifts and drop it into 5th the noise goes away even at 70mph, so i really think it is an internal issue with those gears, I hope a full oil service will help ??

It changes gear and drives smoothly in all gears except for this loud rumbling bearing noise in 6th & 7th which i can also feel through the gear shifter.

I got under it today and there are no visible leaks i also removed & checked the rear gearbox engine mount which is fine so i doubt its a mounting vibration like forum posts have said who had this issue. I've seen it is the deeper new style sump with the larger oval divets, so blue oil and filter are required, which i will get from Merc this week and do a change.

Love this car but it is killing me right now, Ive just done the cam phasers, new alternator, new battery, new disc & pads all round, diff oil, gear selector issue & currently searching for the engine oil leaks from every gasket it seems.....

Im going to start a new thread of this issue

 

[AlanGunn]

Pardon our interruption...

 

[AlanGunn]

You need a fill adapter as well £8 or so.

 

[Adywheels]

You need a fill adapter as well £8 or so.

Thanks, a green one i believe

 

[AlanGunn]

I got one but it was metal.
There is a green plastic part that comes with the kit but that goes on the inside for the fluid level.
Not sure if you need the fill adapter at all but you would need a thinner fill pipe.

 

[Adywheels]

I got one but it was metal.
There is a green plastic part that comes with the kit but that goes on the inside for the fluid level.
Not sure if you need the fill adapter at all but you would need a thinner fill pipe.

Oh yes thanks, I have a manual pump and the metal 109 fill adaptor to go in the sump hole ready to go. I just hope a fluid and filter change fixes this awful noise and it not something wrong in the box as then i'll have wasted £150 on oil etc and have to get it refurbed or another one and the coding done

 

[AlanGunn]

You might want to drain the torque converter.
Easy enough just have to take the pump or whatever off and turn the engine round by the crank until you get the drain plug at the bottom.
Y/Tube it. (you might know all this but i thought i would say anyway jic)..

 

[Adywheels]

You might want to drain the torque converter.
Easy enough just have to take the pump or whatever off and turn the engine round by the crank until you get the drain plug at the bottom.
Y/Tube it. (you might know all this but i thought i would say anyway jic)..

Thanks, i saw a video if this draining, yes it might be worth doing to know it is fully flushed

 

[AlanGunn]

Only 3 or 4 ltr's comes out of the box so worth taking the 4 bolts out to get at the drain for the rest.