Emergency Default Mode, Function - GF27.60-P-3012ANN

Transmission 722.9 05 in model 166 as of model year 2016 

Transmission 722.9 05 in model 292 

Function requirements for limp-home mode, general 

• Circuit 15 ON
• Internal combustion engine running

Limp-home mode, general 

In order to guarantee a safe driving condition and to avoid damage to the automatic 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 is notified to the ME-SFI control unit (N3/10) over the drive train CAN (CAN C). In addition, the ME-SFI [ME] control unit sends an indicator lamp request via the chassis CAN 1 (CAN E1) and chassis CAN 2 (CAN E2) with the electronic ignition lock control unit interface (N73) to the instrument cluster (A1). The instrument cluster activates the engine diagnosis indicator lamp (A1e58). In the event of a hardware fault, all control solenoid valves are switched off and the automatic Transmission switches to 6th gear. After engaging gear range "P" it is possible to engage gear range "R" or "D". 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. The driver can therefore drive the vehicle 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 Xentry Diagnostics.