Hi,

recently I have encountered common issue with my 722.6 gearbox. When cold it is jerky, shifting harsh, when holding lower rpms 1200-1400 rpm it jumps up and down till it shifts to another gear.

I have changed an ATF, connector plug and brand new conductor plate (truckteck company) but sadly nothing has changed.

transmission when hot if I hold accelerator half pressed it does not shift, it holds on 2500rpm and drives like a cvt transmission. When I realease the gas pedal, it shifts the gear to higher but not smooth enough.

i went to local mechanic who has DAS diagnosis system and found few transmission faults:

1.The speed comparison of Y3/6n2 to Y3/6n3 is implausible.

2.The gear is implausible or the transmission is slipping.



sorry for long text, I'm on my way to find solution for it and hopefuly fix it and share with others. Thank you for yout answers!!

 

Y3/6n2 & Y3/6n3 are two rpm sensors on the conductor plate. The errors you have are commonly caused by either or both having failed. However, you indicate that the conductor plate is new. That would tend to indicate a solenoid failure or an internal mechanical failure. Unless you have the tools and expertise to overhaul an automatic transmission, I suggest you find an independent transmission specialist because dealers and most independent mechanic shops will refuse this work because of the labor time involved. Rebuilt transmissions with 3-5 year warranties are also an option.

 

thank you for your answer. What kind of solenoid I should change? What if I buy whole valve body with solenoids in a scrap yard and change it? I have done this procedure on a previous merc I had few years ago

 

RPM sensors are integrated into conductor plate and not replaced separately - current part # 1402701161, what are MB fault codes.

 

Swapping the valve body with solenoids for used may solve the problem, however, the condition of those parts is unknown. ALSO, the problem could be in the clutch packs operated by these solenoids which requires a complete rear down to replace.

Please follow Konigstiger’s lead on this. When he jumps in, I bow out. Konigstiger is THE W211 authority on this forum.