Emergency default mode, function - GF27.60-P-3012AHW
TRANSMISSION 722.9 in MODEL 204.0 as of model year 2009/YoM 08
TRANSMISSION 722.9 in MODEL 204.0 as of model year 2012/YoM 11 model refinement package
TRANSMISSION 722.9 in MODEL 204.2 as of model year 2009/YoM 08
TRANSMISSION 722.9 in MODEL 204.2 as of model year 2012/YoM 11 model refinement package
TRANSMISSION 722.9 in MODEL 204.3
TRANSMISSION 722.9 in MODEL 204.9
Function requirements for limp-home mode, general
- Circuit 87 (connected circuit 15) ON
- Circuit 61 (engine running)
Limp-home mode, general
In order to guarantee a safe driving condition and to avoid damage to the transmission, the fully integrated transmission control unit (Y3/8n4) switches to limp-home mode in the event of critical faults. The fault is stored in the fault memory with the assigned fault code and the engine diagnosis indicator lamp (A1e58) in the instrument cluster (A1) is actuated.
In addition the fault is communicated to the CDI control unit (N3/9) or ME-SFI control unit (N3/10) via the drive train CAN (CAN C).
In the event of a hardware fault, all control solenoid valves are switched off and the transmission switches to 6th gear. It is possible to engage gear range "R, D" after engaging gear range "P".
In gear range "D", the transmission shifts to 2nd gear.
If hydraulic faults occur, the transmission remains in the gear currently engaged.
In the event of control solenoid valve faults, the affected gear is disabled and no longer actuated.
As a result the vehicle can be brought to the nearest Mercedes-Benz service operation.
Diagnosis
Up to 16 faults can be stored simultaneously in the fault memory. These can be read out using the Diagnosis Assistance System (DAS).
| Overview of system components for automatic transmission (AT) | GF27.10-P-9992AHW |