W163 ML270 2002 722.6 won't engage any gears!

LostKiwi

Senior Member
Joined
Aug 25, 2006
Messages
31,328
Reaction score
21,575
Location
Midlands / Charente-Maritime
Your Mercedes
'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
If the selector rod disengaged there would be no resistance to moving the selector lever.
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #22
Ok just removed the two plastic grommets from bell housing to reveal the torque converter , started the car and saw that it at least is spinning .
I can see both ends of selector rod in situ from underneath so both fine thanks
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #23
The only thing I can think to do is remove the oil cooler feed pipe ....put it in a container and start the car.
Just to check that the pump gears / sprocket are in tack and working as it should.
The only thing left I can think of after that is dropping the pan and checking the internal selector linkage is as it should be.
Please keep any suggestions coming.
Thanks
 

LostKiwi

Senior Member
Joined
Aug 25, 2006
Messages
31,328
Reaction score
21,575
Location
Midlands / Charente-Maritime
Your Mercedes
'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
If you start the engine and cycle the selector do you get drive in any gear? Sometimes a box will fail in a failsafe mode where it will drive in a gear.
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #25
No... Nothing... My initial post tells the whole story of the event.... No noise now either or when it first happened
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
Going back to the brake light switch...........

Common symptoms of a defective brake light switch.
  • Car stuck in Park.
  • ABS ESP ETS lights come on.
  • Can not move the shifter from Park to Drive.
  • Brakes Defective Warning on Instrument Cluster
  • Car won’t shift gears. Stuck in 2nd gear, limp mode.
  • Brake lights don’t work. (Brake light switch can still be defective even if the brake lights work. Checking the brake light operation is not a good test.)
  • ESP, BAS, ABS lights turn on. Car won’t shift properly. Stuck in gear.

I've no experience of this personally but as your diagnostics has thrown it up, and it's cheap to do, i'd be inclined to replace it anyway, as it is a known issue.
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #27
As I said the switch is ordered and will be here in a day or two.. I'm also replacing the coolant radiator and the trans oil cooler, just awaiting the cooler so they can be done together...
so apart from the conductor plate etc it could still be a broken gear stick module..or do they have relays etc somewhere that could be an issue... I will test the fluid flow and therefore the trans pump from the oil cooler feed tomorrow and I'll nvestigate the gear stick module... thanks guys, keep it coming
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #28
I would imagine that speed sensor or sensors...not sure how many are at the wheels, could also be the issue...especially if there is not one on every wheel...just can't imagine it will be sensor on the conductor plate as that was changed not to long ago...just a thought?
I have no issue in taking the trans out if needs be...just trying to eliminate everything prior to digging that deep
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #30
Ok ...thanks for that
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
I keep coming to the same conclusion, and that is that the engine and transmission has been electronically disabled, the question is why? I've experienced total TCU failure but i still had first gear. Drive would engage with a clunk and disengage with a clunk and felt very mechanical, but it engaged. Changed the TCU and we were back In the game. You have nothing.

Your low voltage could be a consequence of the brake light switch but don't know how the power is fed.
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
I'll see if i can identify circuit 87, i have some drawings in my icarsoft software. I'll try and do it this evening.
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
I'll see if i can identify circuit 87, i have some drawings in my icarsoft software. I'll try and do it this evening.
1502569576162-1246932247.jpg This drawing shows the brake light switch as S9. Taking its live from F15, through relay K6, through S9 brake light switch and onto N15/5, which is your electronic selector control module. Some stuff to check if you feel so inclined.
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #34
Sorry I've been preping the car for paint today so not been online while I await the brake switch and oil cooler before I test the trans pump is functioning....I really appreciate you sticking with this...yeh any avenues to go down I'm very much inclined to do the work
Thanks again
 
OP
Blueyes1971

Blueyes1971

Senior Member
Joined
Dec 3, 2010
Messages
238
Reaction score
37
Location
Midlands
Your Mercedes
2002 ML270 CDI Facelift
  • Thread Starter
  • Thread starter
  • #35
I'm wondering that even though the selector is connected to the rod and the trans, the fact that it's electronic and the selector is an electronic module say.... Then there's a possibility it sends its signal to the trans ecu in order to engage... Even if the mechanical side is correct it will actually only engage if the electronic signal to the ecu then onto the trans is functioning... Resulting in no gears if selector module is down.... May have to investigate how to test the selector itself
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
I'm wondering that even though the selector is connected to the rod and the trans, the fact that it's electronic and the selector is an electronic module say.... Then there's a possibility it sends its signal to the trans ecu in order to engage... Even if the mechanical side is correct it will actually only engage if the electronic signal to the ecu then onto the trans is functioning... Resulting in no gears if selector module is down.... May have to investigate how to test the selector itself
That's correct. The shifter stick is connected to a hydraulic valve and nothing more. The 722.6 is a planetary gear system so no gears actually move. The transmission works through opening clutches or applying brakes, or both, locking some gears in place and/or allowing others to rotate. Does take some time to get your head around.

The gearshift stick is also electronic and is tied into the brake light switch, hence the drawing, its also part of the CAN which is the high speed communication network.
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
So, the gearshift module is electronicly connected to the TCU, which is the transmission module, also connected to the engine ECU, which is why you have lost your accelerator, its been disabled by the TCU.

If the drawing I sent is correct the power for the gearshift module is provided by the brake light switch, so if the brake light switch is buggered, a known issue, then it may be the case that the gearshift module is getting no power, hence the low voltage code.

The TCU can't see the gearshift module because it has no power, and simply shuts down the gearbox and the engine to save further damage.

And, your going nowhere.
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
Our American friends have a habit of spilling pop on the gearshift and it runs down into the electronics, and fries them. Big problem over there.
 

Arudge

Senior Member
Joined
Jun 14, 2016
Messages
753
Reaction score
246
Location
Cradley Heath
Your Mercedes
CLK200 2000 Kompressor
From memory, the gearshift is mechanically connected to the master shift valve which in turn recieves oil pressure from the modulating valve. The transmission oil pump is mechanical so always pumps, but if the modulating valve is disabled or held wide open, dumping all pressure back to tank then the master shift valve is useless, there's no pressure so nothing moves.
 

Avantgarde Automotive, Mercedes-Benz and SLR McLaren specialists. Service, repairs, diagnosis and motorsport preparation.
Unit 14 Hither Green Trading Estate, Clevedon, Somerset, BS21 6XU Tel: 01275 217270 Email:steve@avantgarde-automotive.co.uk
www.avantgarde-automotive.co.uk
Top Bottom