Generation of diagnostic trouble codes:: Notes
- Fuel level, Plausibility diagnosis:
Because fuel level is used as an enable criteria in certain diagnosis, then the control module must know that fuel level value is plausible. It works in such a way that Trionic receives the bus message "Fuel level XX liter" from MIU. While driving Trionic observes the value and as the vehicle is driving it is consuming petrol, Trionic sees that the fuel level value will fall. In Trionic there is a number of filtrations of the value so as to avoid inaccuracies due to for example splashing fuel in the tank and hill starts. The fuel level diagnosis can be said to be a support diagnosis, it does not generate its own diagnostic trouble codes, but if for example the tank pressure sensor diagnosis has reported a performance problem in the tank pressure sensor then DTC P1451 is normally generated. If on the other hand the tank pressure sensor diagnosis has reported the same fault and the fuel level diagnosis at the same time has also reported a fault then DTC P1491
is generated instead.
Diagnostic trouble codes are generated if the fault criteria are fulfilled and the dependents are OK.