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

TRANSMISSION 722.9 in MODEL 166 up to model year 2016 

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 with the fault code assigned to it in the fault memory and sent to the CDI control unit (N3/9) (with diesel engines) or the ME-SFI [ME] control unit (N3/10) (with gasoline engines) via the drive train CAN (CAN). In addition, the CDI control unit or the ME-SFI [ME] control unit sends an indicator lamp request via chassis CAN 1 (CAN E1) and chassis CAN 2 (CAN E2) with the electronic ignition lock control unit interface (N73) to 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 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 Xentry Diagnostics.