W203

[Neepneep]

2006 W203 C180 Kompressor Estate (2nd owner, bought at 60k now 105k)

Gearbox.... there's a tinny vibration in centre console. Not always. Started near 90k miles and usually only comes if car has done 20+ miles in that day. I've been ignoring as sometimes never happens. When it does happen, once you reduce from say 20mph or below - you will hear the tinny sound change into a rusty kind of spinning, it will be SLOWING, wih the car. Noise/vibrations of gearbox then stop.

TODAY, my shifter stuck in P/R after a 5 point turn. Would not go into N (or D). Turned key off/on for while done everything. Friend wobbled my car as I wobbled gear stick and it done it went through R to P and drove home.
This PRIOR happened ONCE before 3mths ago. That time, car was parked first (3 or 5 point turn also) after 30mile long drive. Parked 1hr. Went to leave and car wouldn't come out of P. Wobbled and swore at it for 10mins and it worked, went into R, and drove off in D.


Now TODAY when it jammed, as said, my friend wobbled my car using high tech wobbling skills. Got the car home, tried the gearstick around for 30mins. Now wouldn't go from N into R (or P). Only have D and N. Key fob stuck in. I've left in N, engine off,. I have taken backup metal key out of "key fob" and secured car as locked. Before tht I drove around for in D, changing gears manually + auto, all fine. Just every time I stop and go for R/P it just will not move across. Taptronic DOES work when driving. Automatic changes are nippy.

I'VE OPENED IT UP also..
My leather/plastic gearstick cover (console) has been loose since bought. Couple of plastic clips inside had snapped where they meet centre console piece. Perhaps previously opened? Had a go at pulling out the shifter cover, unplugged (and later re-plugged + tested) the 2 red cables within the gear selector unit. (Not big white TCU plug).
Hoovered inside. Evidence inside agreeing to some spilled liquid seeped via side of console but wiped fast at the time.
Turned engine back on and some "computer" type noises in dash or somewhere in the car that don't usually happen.
Also took out centre console and found backup shifter release tab. It seems to work by pushing back IN a piece of metal that is already in when in Park I assume.
Now I am stuck in Drive, Neutral. Trying to move into R.
The shifter release tab inside the moduel, usses a pivoting plastic piece that you push - and it pushes almost a bullet in towards the gear box.
These "bullets" are already "inside" at D or N. When I move from N to R, that bullet them wants to come out. I imagine that bullet (release catch) is only for escaping park to tow in N. I don't think it helps this problem of stuck in D/N.

Other things I've see online:

1. Defective Brake Light Switch
2. Low Voltage or Dead Battery
3. Spilled Liquid on the shifter assembly
4. Defective shift interlock solenoid
5. Faulty Engine Control Unit (ECU) or Transmission Control Unit (TCU)
6. Transmission Shift Cable Broken or Shift Rod Bent / Loose
7. Plates

Quite common for the electro-plate to fail with sensor faults.
Quite common for the pilot bush connector to allow atf to travel up the loom to the ecu and kill it

 

[Neepneep]

Also took out centre console and found backup shifter release tab. It seems to work by pushing back IN a piece of metal that is already in OUT when in Park I assume. Hence why pushing the clip in, forces the pin in and releases you from the "Park" gear safety system.
Now I am stuck in Drive, Neutral. Trying to move into R. The pin isn't out, at D or N, as safety system is for Park.
If you are in Neutral, the pin will be in. But if you move towards R, the pin wants to come out. Blocking that only feels like resisting. I think that override shifter release tab is purely for those stuck in P who N to be towed.

 

[Numair Aidroos]

I don't know about this version of the C class or any C from any generation. Expert members will guide you in the right direction. On the w221 from 2006 to 2014, there is an ISM unit that decides the shifter input to be output at the transmission level. If such is the case with your C class then it's likely the relay for the ISM or the unit itself.

Before trying anything, get a hold of a Star Mercedes Benz diagnostic computer and scan the car thoroughly twice. Then proceed with fixes.

 

[Petrol Pete]

Welcome along . OP , you are on the right track checking the TCU plug etc but getting the codes read is a must. Also keep an eye out for rust . The obvious places on this model are the wheel arches (forward part of the rear arch being the worst) and the hidden one in the tailgate. And rusty brake lines hidden under the undertray running the length of the car.

Pi$$ poor design leaves salty road road residue in the small foam 'gaskets' on the rear number plate lamps where it sits quietly corroding away , basically the foam (instead of rubber...why ?) gaskets hold the water/salt/gunk.

The best way to check it is to remove the inner lining from the rear hatch and have a very good look around with a torch,If looking from the outside where the lamps fit in you can miss it.

 

[Stratman]

foam (instead of rubber...why ?)

Foam gasket cost €0.000002
Rubber gasket cost €0.000003

 

[Neepneep]

I called the MB specialist that done my timing chain and head. He said, the tinny vibration that changes at low speed/stopping, is probably broken parking brake clip rubbing on propshaft. He said he's seen that loads of times and most likely the issue.
The gear shifter... he said it's probably the shifter itslf and may need new module. Because the car changes gear normally otherwise and taptronics work.. seems to be the shifter itself. Advised me to go MB new or get 2nd hand and maybe call him to fit it.
I mean... should I be looking at simpler issues before replacing whole module (circa £600)... or trust these guys? I take it they might look for some of the simpler faults anyway. Though they said they are full can't take any cars for 3 wks.