Engine limp-home mode, function - GF07.10-P-1019OM
ENGINE 651.9 in MODEL 204
ENGINE 651.9 in MODEL 207, 212 (except 212.098/298) up to model year 2014
ENGINE 651.9 in MODEL 218 up to model year 2014
Function requirements for engine limp-home mode, general points
- Circuit 87M ON (engine timing ON)
- Engine running
Engine limp-home mode, general
The task of the engine limp-home mode consists of ensuring continued safe driving in the case of malfunctions on individual components of the engine timing system.
The CDI control unit (N3/9) controls engine limp-home mode based on the following sensors and signals:
- Camshaft Hall sensor (B6/1)
- Accelerator pedal sensor (B37), accelerator pedal position
- Crankshaft position sensor (L5) (except code (B03) ECO start/stop function), engine rpm
- Electronic Stability Program control unit (N30/4) (except code (233) DISTRONIC PLUS) or Electronic Stability Program Premium control unit (N30/7) (with code (233) DISTRONIC PLUS) (except model 204), brake actuation via the chassis CAN
- Electronic transmission control control unit (N15/3) (with code (423) 5-speed (NAT) A/T), gear range via the drive train CAN (CAN C)
- Fully integrated transmission control controller unit (Y3/8) (with code (427) 7-speed A/T), gear range via drive train CAN
The Electronic Stability Program control unit will be used in service as of 1.3.2011 (model 204.0/2.) or as of 1.6.2011 (model 204.3) in 2 variants:
- Electronic Stability Program control unit, basis variant (except code (233) DISTRONIC PLUS)
- Electronic Stability Program Premium control unit, standard variant (with code (233) DISTRONIC PLUS)
Until 28.2.2011 (model 204.0/2.) or 31.05.2011 (model 204.9) and as of 1.6.2011 (model 204.9) only the basic variant of the Electronic Stability Program control unit will be used.
If the plausibility check made by the CDI control unit is negative or if both Hall sensors fail, the system will only work to regulate the idle speed.
Function sequence for limp-home mode when crankshaft position sensor fails (except code (B03) ECO start/stop function) or crankshaft Hall sensor (with code (B03) ECO start/stop function)
If no voltage signal is received from the crankshaft position sensor or crankshaft Hall sensor, the voltage signal from the camshaft Hall sensor will be used instead (for limp-home mode).
Diagnosis
Faults detected by the accelerator pedal sensor are stored in the fault memory and can be read out and cleared using Xentry Diagnostics.
| Electrical function schematic for engine limp-home mode | MODEL 204 | PE07.10-P-2719-97FAE | |
| Electrical function schematic for engine limp-home mode | MODEL 207 | PE07.10-P-2719-97EAE | |
| Electrical function schematic for engine limp-home mode | MODEL 212 | PE07.10-P-2719-97DAE | |
| Electrical function schematic for engine limp-home mode | MODEL 218 | PE07.10-P-2719-97XAD | |
| Overview of system components for common rail diesel injection (CDI) | GF07.16-P-9997OM |