1.13.2.3 Monitoring Function - Mechanical Chain Jump Diagnosis

P13BA/P13BB, P13BC/P13BD 

The diagnosis is performed after the reference position adaptation. The learned position of each camshaft signal edge is stored in the non-volatile RAM of the ECU as an adaptation value. Before storing the value, the new adapted value is compared to the stored value. When the deviation exceeds a maximum value, the error CAM_one_tooth_off is delivered to error management and the new value is not stored in RAM. A chain jump of the timing chain is detected with this diagnosis.

The diagnosis of the mechanical chain jump has an interface to the Rate-Based Monitoring Module.

1. In-Use Monitor Performance Ratio:

   The incrementing of the numerator and denominator for the chain jump diagnosis is executed by the Rate-Based Monitoring Module. Like all monitors for which a standardized track and report in-use performance is required, the diagnosis monitor reports to the Rate-Based Monitoring Module via status flags.

2. Conditions for incrementing the Numerator:

   The numerator is incremented only when stored faults do not inhibit the monitor and when the diagnostic has been performed and a fault could have been detected.

3. Conditions for Incrementing the Denominator:

   The denominator is incremented with every driving cycle.