Rockup functional breakdown decision manner null of oil control

摘要

PURPOSE: To improve self-diagnosis function by determining failure of a lockup control mechanism based on failure determination areas which are set based on an engine negative pressure condition, an engine operation condition and a car running condition. CONSTITUTION: During running of a car, signals are inputted to a control means 80 from a throttle opening sensor 82, a car speed sensor 84, and an engine negative pressure sensor 86. The control means 80 determines failure of a lock-up mechanism by means of a failure determination part 80a, based on an ON failure determination area and an OFF failure determination area which are set based on an engine load condition, an engine operation condition and a car running condition It is namely determined the ON failure where a lock-up solenoid valve 42 is set ON despite OFF command is output to a lockup solenoid valve 42, and the OFF failure where the valve 42 is set OFF despite the ON command is output to the valve 42. Failure determination of the lock-up control mechanism is performed by confirming a ratio between an engine speed and car speed.