Abstract: A detector and battery switch control energy flow from a battery in a vehicle to an electronic module. The vehicle ignition switch controls battery energy flow when the ignition switch is on and the detector and battery switch control battery energy flow when the ignition switch is off. A dimming circuit provides a dimming signal when a demand for energy is made, such as when the headlights are turned on with the ignition switch turned off. The detector senses the dimming signal and operates a battery switch to power up a microprocessor controller from an unpowered state to control operation of the module when the demand for energy is made. There is no sleep mode. A response is made directly to the demand for energy and there is no battery power used until a demand is made for battery energy.

Abstract: Two electronic modules are connected to share and to independently read the sensed value from a single environmental sensor element, by communicating between each other when a particular module is reading the sensor output signal. The sensor output signal is a function of the value of the reference voltage being applied by the reading module and the characteristics of the environment being sensed. A module provides a toggle signal when it completes its reading of the sensor so that the other (non-reading) module will know when it may apply its reference voltage to the sensor and complete its reading of the sensor. The modules alternate the reading of the sensor in order to eliminate the need for a plurality of corresponding sensors.

Abstract: A low cost, less complex microcomputer power supply circuit with temperature stability and low current consumption in which a single voltage regulating element is used to provide the supply voltage, power-on reset (POR) and low voltage inhibitor (LVI) functions to the microcomputer (12). In an exemplary embodiment, the power supply circuit (10) includes a regulating circuit with a zener diode (30) that is conductive when the voltage level of the DC source (14) is above a threshold value and nonconductive when the voltage level of the DC source (14) is below a threshold value. The regulator circuit provides a regulated supply voltage to the microcomputer from the DC source (14). The regulator circuit also provides a regulation signal, whose state depends on the conductivity of the zener diode (30), to a reset circuit. The reset circuit of the power supply circuit is responsive to the regulation signal for providing a reset signal to the microcomputer (12).

Abstract: A short circuit protection system that reacts to a voltage across an electrical load to prevent overdissipation of a semiconductor switch in the event of a short circuit. The system includes a capacitor having a charge state. When the capacitor is charged, the electrical load is turned ON via a transistor. The system automatically latches the electrical load ON until a short circuit occurs or until the capacitor discharges. When a short circuit occurs, the system automatically turns the load OFF.

Abstract: Apparatus for testing wiring harnesses either during or after the harness fabrication process comprises test points, each of which is connected to a corresponding terminal of the harness. Associated with the test points are a current source, a current sourcing means, a current sink, and a current sinking means. Each current sourcing means and current sinking means comprises a controlled conduction path which is selectively operable to a conductive state or a non-conductive state. The tester operates to test individual circuits of the harness for continuity and shorts. In doing this the controlling conduction paths are selectively operated in accordance with information correlating the wiring harness circuits with the test points. A current sensing means senses the present or absence of current during open and short circuit tests and provides appropriate indicator signals to indicate opens or shorts if such faults are present.