Apparatus and method for diagnosing faults in a vehicle electrical system
First Claim
1. An apparatus for diagnosing a fault within the electrical system of a vehicle, said electrical system including a system control unit connected to a plurality of electrical components through an interface, said interface including a plurality of electrical leads connected to said components, said apparatus comprising:
- a first signal generator for generating an a.c. test signal;
a switching means coupled to the first signal generator and to the interface for sequentially applying said a.c. test signal to the electrical leads except for an electrical lead connected to a common of the electrical system to generate a system output at the common;
a first detector means connected to the electrical lead connected to the common for detecting a set of transitory characteristics of the vehicle electrical system based on the response of said vehicle electrical system to the application of said a.c. test signal to the electrical leads;
a storage means for providing a stored set of reference characteristics for said vehicle electrical system;
a comparator means for comparing the detected transitory characteristics with the stored set of reference characteristics; and
a processor means responsive to said comparator means for diagnosing the presence of at least one fault when the detected transitory characteristics of the vehicle electrical system deviate significantly from the stored set of reference characteristics for said vehicle electrical system.
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Accused Products
Abstract
An apparatus for diagnosing the presence and location of faults within a vehicle'"'"'s electrical system includes a signal generator for generating an a.c. test signal; a switching circuit connected to an interface between the system'"'"'s ECU and the system'"'"'s components for selectively and sequentially applying the a.c. test signal into each electrical lead therein; and a first detector connected to the system'"'"'s common ground for detecting the system'"'"'s response to the applied signals, thereby obtaining a set of transitory characteristics for the vehicle'"'"'s electrical system. The apparatus further includes an EPROM within which a set of reference characteristics for the vehicle'"'"'s electrical system is stored; a comparator means for comparing the detected transitory characteristics with the stored set of reference characteristics; and a diagnostic processor responsive to the comparator means for diagnosing the presence of a fault when the detected transitory characteristics of the vehicle'"'"'s electrical system deviate significantly from the stored set of reference characteristics therefor. Upon diagnosing the presence of a fault within the vehicle'"'"'s electrical system, a d.c. test signal is injected under the control of the diagnostic processor using the switching circuit only into the lead or leads of the interface deemed responsible for the deviant system output. A second detector likewise connected by the switching means only to those leads deemed responsible for the deviant system output detects the reflection of the d.c. test signal for use by the diagnostic processor in determining the location of any existing fault relative to the interface.
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Citations
12 Claims
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1. An apparatus for diagnosing a fault within the electrical system of a vehicle, said electrical system including a system control unit connected to a plurality of electrical components through an interface, said interface including a plurality of electrical leads connected to said components, said apparatus comprising:
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a first signal generator for generating an a.c. test signal; a switching means coupled to the first signal generator and to the interface for sequentially applying said a.c. test signal to the electrical leads except for an electrical lead connected to a common of the electrical system to generate a system output at the common; a first detector means connected to the electrical lead connected to the common for detecting a set of transitory characteristics of the vehicle electrical system based on the response of said vehicle electrical system to the application of said a.c. test signal to the electrical leads; a storage means for providing a stored set of reference characteristics for said vehicle electrical system; a comparator means for comparing the detected transitory characteristics with the stored set of reference characteristics; and a processor means responsive to said comparator means for diagnosing the presence of at least one fault when the detected transitory characteristics of the vehicle electrical system deviate significantly from the stored set of reference characteristics for said vehicle electrical system. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for diagnosing a fault within the electrical system of a vehicle, said electrical system including a system control unit connected to a plurality of electrical components through an interface, said interface including a plurality of electrical leads connected to said components, said method including the steps of:
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sequentially applying an a.c. test signal to the electrical leads except for an electrical lead connected to a common ground of the electrical system to generate a system output at the common ground; detecting the system output responsive to said application step at the electrical lead connected to the vehicle common ground to obtain a set of transitory characteristics of said vehicle electrical system; providing a stored set of reference characteristics for said vehicle electrical system; comparing the set of transitory characteristics with the stored set of reference characteristics and diagnosing the presence of at least one fault when the set of transitory characteristics of the vehicle electrical system deviate significantly from the stored set of reference characteristics for said vehicle electrical system. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification