Specification of the Fault Memory Status (pseudo fault reduction)
In certain vehicle operating situations invalid fault memory entries (pseudo faults) are made as the control units do not behave synchronously in these situations. The critical operating situations occur during
- Wake-up of the vehicle
- Start of the combustion engine
- Under/Overvoltage
To prevent pseudo faults in these operating situations, a centrally communicated signal forbids specific faults from being entered in the local fault memories of the control units.
These will simultaneously actively prevent these faults being signalled to the master of the "storage system context" function and from being entered in the central fault memory.
The fault memory block is not only effective for network fault memory entries, however not for control units-fault memory entries.
The fault memory entries for control units relevant for exhaust gas and safety are not affected by this function and they will always be written.
Scheme 34
| Index | Explanation |
|---|---|
| 1 | Under/Overvoltage block condition: 10.5 V < U < 16 V Unblock condition: U > 11 V or U < 15.5 V |
| 2 | Junction Box (master for the subfunction specification of fault memory status) |
| 3 | Bus message "status - block fault memory" |
| 4 | All control units |
| 5 | Wake-up of the vehicle Block condition: wake-up signal Unblock condition: three seconds after wake-up signal tw > 3 s |
| 6 | Engine start (Terminal 50) block condition: Terminal 50 active |
INDEX CHART