Patent ID: 8868282

Claim:
A diagnostic system for diagnosing a device of a vehicle, comprising: a first electronic circuit configured to generate samples of a parameter of the device; a second electronic circuit configured to indicate whether each of the samples passed or failed based on comparisons of the samples with one of a predetermined value and a predetermined range; a third electronic circuit configured to track a first number of consecutive samples compared, to track a second number of the first number of samples that failed, to track a third number of the first number of samples that failed consecutively, and to track a fourth number of a last predetermined number of samples compared that failed, wherein the second electronic circuit is further configured to: select one of a normal control mode, a temporary default action mode and a permanent default action mode based on the first, second, third, and fourth numbers; transition from the normal control mode to the temporary default action mode and takes a temporary default action based on at least one of the third and fourth numbers; transition to the permanent default action mode and takes a permanent default action based on at least one of the first, third, and fourth numbers; and selectively set a diagnostic trouble code (DTC) in memory when in the permanent default action mode.