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[722.9] How to test the TCU ?

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by desmofab, Aug 30, 2019.

  1. desmofab

    desmofab Member

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    CLK W209 / 2006 / 320 CDI (OM642) + 722.9
    Hello all,

    For the second time in two months my car let me on the side of the road.

    I have been riding more than 1000 km in one week and for the final step of my trip it was impossible to start the engine.
    On the dashboard, I do not have the gearbox information like (P R N D). I used an autocom and faults code are the following : P1856, P2211, P1221.

    So I changed the gear selector, now the car is able to start but the car is staying on the first speed. P2211, P1221 are remaining. To test the TCM I unplugged the wire one the gearbox (722.9) and I got the same symptoms but with the fan running a lot in addition.

    As an information, I bleed the oil of the rear tranmission and the gearbox one month ago(2000km).

    From WIS electical diagram I made some continuity tests. And everything seems ok from/out N15/3 and N15/5

    I also checked the K relay into the front sam and I made a swap with the horn relay... Without succes. Still no gear displayed on the dashboard !

    I also checked the can bus X63/4.


    Now I removed the TCU but I still have some doubt about the root cause... maybe I missed something..


    Do you have any advice ?

    Thanks


    IMG_20190822_215946.jpg
     
  2. OP
    desmofab

    desmofab Member

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    I am going to change front SAM... "in case of"..
     
  3. Botus

    Botus Senior Member

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    not saying this is your issue....

    but did u try searching for those fault codes

    Common Faults:
    Mercedes C-Class C220 GRM (gear recognition module) will cause a failure to select gear when faulty. Ignition cycle may intermittently clear the fault but once faulty it will gradually worsen until permanent. P240C-The CAN signal for the selector lever position from component N15/5 (electronic selector lever module control module) is implausible and P1856 - selector lever position detection has failed are fault codes commonly stored.

    or

    https://forums.mbclub.co.uk/threads...n-detection-has-failed-w211-e220-2004.242177/
     
  4. OP
    desmofab

    desmofab Member

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  5. Botus

    Botus Senior Member

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    the electro plate normally gives distinct codes with Y3 ones being common, how good is your diagnostic kit?


    CONTINENTAL 7G-TRONIC (722.9) fault codes

    •Y3/8N1 – Turbine speed sensor
    •P0717 – The signal from component Y3/8n1 (Turbine speed sensor (VGS)) is not available
    •P0718 – Component Y3/8n1 (Turbine speed sensor (VGS)) is defective
    •Y3/8N2 – Internal speed sensor
    •P2200 – The signal from component Y3/8n2 (Internal speed sensor (VGS)) in not available
    •P2201 – Component Y3/8n2 (Internal speed sensor (VGS)) is defective
    •P2767 – The signal from component Y3/8n2 (Internal speed sensor (VGS)) in not available
    •P2768 – Component Y3/8n2 (Internal speed sensor (VGS)) is defective Other internal speed sensor error codes: P2204, P2205, P2206, P2207
    •Y3/8N3 – Output speed sensor
    •P0722 – Output Speed Sensor No Signal
    •P0723 – Output Speed Sensor (VGS) is defective
    •Y3/8S1 – Transmission range sensor
    •P0705 – Transmission Range Sensor Circuit Malfunction
    •P2716 – Pressure Control Solenoid “D” Electrical


    https://www.actronics.co.uk/tcu/continental-7g-tronic-722-9-first-second-and-third-generation
    whilst you can repair most of the issues they have one that's unrepairable in my mind a new one would be a better idea
     
  6. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    Ideally, you needed to have attempted to read the codes from the TCU before removing it.

    It has either a can comms fault, or a speed sensor fault, but as its sitting out of the car, you will have to refit to determine which. :)
     
  7. OP
    desmofab

    desmofab Member

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    My main concern is can communication cannot be established with the the gearbox.

    I made the oil bleed and with the same autocom I was able to got gearbox oil temperature.

    Unfortanetlly my TCM is the first GEN and it cannot be sold without the valve body.... I think the next destination for my car is to the breaker's yard
     
  8. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    They can be repaired, depending on failure.
    Otherwise, a second hand electroplate can be virginised and reprogrammed for your car.

    No need to take the car to the breakers yard
     
  9. OP
    desmofab

    desmofab Member

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    I hope you are right !
     
  10. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    I do it every day, so I hope so :p
     
  11. ajlsl600

    ajlsl600 Senior Member

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    where in france are you?
     
  12. OP
    desmofab

    desmofab Member

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    Help all,
    To close that topic.

    The gearbox specialist wasn't able to deal with the tcm too. In spite of, he changed all the sensors but without any improvement.

    For him the tcu is out of service... If one day I have to change my job I could work as MB gearbox specialist too. ;)


    So, died for died I decided to open the tcu and ... it was full of oil...

    I will post a picture of the motherboard..

    For a small electric circuit my car will finish to the breakers yard :/

    So sad, I really loved that car !

    I am near from Paris.
     
  13. ajlsl600

    ajlsl600 Senior Member

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    bad luck and crap design that oil travels in the loom... i am in normandy, a bit far from you.sorry maybe you can get a used tcu, but due to design you would still get stung for coding that....
     
  14. OP
    desmofab

    desmofab Member

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    Where in Normandy ? I am living at the border with Normandy and work at Cléon and Le Havre;)
     
  15. pgh13

    pgh13 Senior Member

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    Clutching at straws, have you tried to clean up the tcu? I think I saw a YouTube where they used a degreasant wash. What’s to lose?
     
  16. OP
    desmofab

    desmofab Member

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    I already tried without success...

    I am living at the border with Normandy and work at Cléon and Le Havre, You could help me ?
     

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  17. ajlsl600

    ajlsl600 Senior Member

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    i am 15 min south of saint lo , think yr prob best bet is a used tcm .cleared and reprogrammed for yr car as suggested above by alex. maybe he could supply one. its a shame to dump the car for this, maybe a car breaker can supply one from the same model? i have star , but as advised once its in bits its not possible to get the information needed and i am not sure but doubt one can reprogramme off-line ??
     
  18. OP
    desmofab

    desmofab Member

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    Ok I will give a last chance to my car !

    I watched some video about TCM clearing procedure but is not totaly clear for me and I do not have the good couple of software/ hardware to do that.

    I found an used TCM on ebay but I would like to got a clear procedure before purchasing it.
    Alex do you have any tricks for me ?
     
  19. alexanderfoti

    alexanderfoti MBO Forum Supporter Authorised Forum Supporter

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    You will need to have somebody carry out a virginise procedure on it. I am happy to so it for a nominal fee and then ship it to you?

    Once done you installs and code it to the car with STAR. It needs full online star to scn code it.
     
  20. OP
    desmofab

    desmofab Member

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