Malfunction diagnosing apparatus for electronic control system for vehicles

In combination with an electronic control system for vehicles, said electric control system having a battery, a sensor energized by said battery for converting a sensed vehicle condition into an electric condition voltage, an actuator having a winding energizable by said battery for controlling a vehicle operation, and an electronic calculation unit connected between said sensor and said actuator, for producing a pulse signal which enables said winding to be energized in response to said electric condition voltage, a malfunction diagnosing apparatus comprising:

• first connecting means detachably connected to said sensor for deriving a voltage supplied to energize said sensor;
• first comparing means for comparing said voltage derived by said first connecting means with a first reference value indicative to an allowable minimum energizing voltage;
• first memorizing means for memorizing a malfunction in response to a first output of said first comparing means, said first output being indicative of said voltage derived by said first connecting means being smaller than said first reference value;
• first displaying means for displaying said malfunction memorized by said first memorizing means;
• second connecting means detachably connected to said actuator for deriving a voltage proportional to a current flowing through said winding when said pulse signal is produced by said electronic calculation unit;
• second comparing means for comparing said voltage derived by said second connecting means with a second reference value indicative of a required minimum energizing current;
• second memorizing means for memorizing a malfunction in response to a second output of said comparing means, said second output being indicative of said voltage derived by said second connecting means being smaller than said second reference value;
• and
• second displaying means for displaying said malfunction memorized by said second memorizing means.