Emergency default mode, function - GF27.60-P-3012AHS

TRANSMISSION 722.9 in MODEL 216.3 as of model year 2009 / YoM 08 

TRANSMISSION 722.9 in MODEL 216.3 (except 216.374) as of model year 2011 /YoM 10 model refinement package 

TRANSMISSION 722.9 in MODEL 221.0 as of model year 2009 / YoM 08 

TRANSMISSION 722.9 in MODEL 221.0 (except 221.095) 

TRANSMISSION 722.9 in MODEL 221.0 (except 221.074) as of model year 2011 /YoM 10 

TRANSMISSION 722.9 in MODEL 221.1 as of model year 2009 / YoM 08 

TRANSMISSION 722.9 in MODEL 221.1 (except 221.195) 

TRANSMISSION 722.9 in MODEL 221.1 (except 221.174) as of model year 2011 /YoM 10 

Function requirements for limp-home mode, general 

• Circuit 87 ON
• Circuit 61 (engine running)

Limp-home mode, general 

In order to ensure safe driving and to prevent damage to the transmission, the fully integrated transmission control unit (VGS) (Y3/8n4) switches to limp-home mode in the event of critical faults. The malfunction is filed along with the assigned fault code in the fault memory and the engine diagnosis indicator lamp (A1e58) in the instrument cluster (A1) is actuated over the central CAN (CAN F).

The malfunction is also communicated via the drive train CAN (CAN C) to the ME-SFI [ME] control unit (N3/10) in vehicles with gasoline engines or to the CDI control unit (N3/9) in vehicles with diesel engines.

In the event of a hardware fault, all control solenoid valves are switched off and the transmission switches to 6th gear.

After gear range "P" is engaged, gear range "R and D" can be engaged.

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 with DAS.

Overview of system components for automatic transmission (AT)

GF27.10-P-9992AHS