The present invention relates to an accumulated error time monitoring diagnostic control system. A diagnostic system includes N dedicated diagnostic modules that each correspond with a respective one of multiple control systems. The N dedicated diagnostic modules each generate status signals indicating results of respective diagnostic tests. A diagnostic error time monitor determines an accumulated error time value between error events for each of the control systems based on the status signals. The diagnostic error time monitor selectively reports a fault to a respective one of the N dedicated diagnostic modules based on the accumulated error time value.
Accumulated error time monitoring diagnostic control system