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

TRANSMISSION 722.902 /903 /904 /906 /907 in MODEL 164.1 as of Model Year 09 /Modification year 08 Model refinement package 

TRANSMISSION 722.902 /903 /904 in MODEL 164.8 as of Model Year 09 /Modification Year 08 

TRANSMISSION 722.902 /904 /906 /999 in MODEL 251.0 as of Model Year 09 /Modification year 08 

TRANSMISSION 722.902 /904 /906 /999 in MODEL 251.1 as of Model Year 09 /Modification year 08 

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 fault is stored in the fault memory with the assigned fault code, and the CHECK ENGINE indicator lamp (A1e26) (with code (494) USA version) or the engine diagnosis indicator lamp (A1e58) (except code (494) USA version) is actuated in the instrument cluster (A1). In addition, the fault is sent to the ME-SFI control unit (N3/10) in the case of gasoline engines or to the CDI control unit (N3/9) in the case of 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 using the Diagnosis Assistance System