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Testing wiring harnesses

  • US 4,689,551 A
  • Filed: 09/05/1985
  • Issued: 08/25/1987
  • Est. Priority Date: 09/05/1985
  • Status: Expired due to Term
First Claim
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1. Means for testing individual circuits of a wiring harness wherein each individual circuit is intended to be electrically independent of the others and each such individual circuit comprises two or more termination points, said testing means comprising a plurality of test points, each for connection to a corresponding particular one of the termination points of a harness'"'"' circuits, a current source for supplying source current, a current sourcing means for selectively sourcing current from said current source to said test points and thereby selectively to a harness'"'"' termination points, a current sink, current sinking means for selectively sinking current from said test points and hence selectively from a harness'"'"' termination points, means for operating said current sourcing means and said current sinking means to selectively perform open circuit and short circuit tests on the individual circuits of a harness, said current sourcing means comprising a plurality of independent controlled conduction paths, each containing its own independent controlled conduction device operably coupled from said current source to a corresponding particular one of said test points, said current sinking means comprising a plurality of independent controlled conduction paths, each containing its own independent controlled conduction device operably coupled from a corresponding particular one of said test points to said current sink, means for operating each of said independent controlled conduction devices selectively to conductivity and non-conductivity states independently of the other independent controlled conduction devices, means for performing an open circuit test on an individual circuit of a harness by operating to the conductivity state the corresponding particular controlled conduction device of said current sourcing means to which a particular one of the termination points of the particular individual circuit under open circuit test is connected, by also operating to the conductivity state the corresponding particular controlled conduction device of said current sinking means to which another of the termination points of the particular individual circuit under open circuit test is connected, and by also operating to their non-conductivity states at least all others of said controlled conduction devices to which termination points of the harness under test are connected, means for performing a short circuit test on an individual circuit of a harness by operating to the conductivity state the corresponding particular controlled conduction device of said current sourcing means to which a particular one of the termination points of the individual circuit under short circuit test is connected, by also concurrently operating to their non-conductivity states the corresponding particular controlled conduction devices of said current sinking means to which all other termination points of the particular individual circuit under short circuit test are connected, by also concurrently operating to their non-conductivity states at least all other controlled conduction devices of said current sourcing means to which the remaining termination points of the harness under test are connected, and by also concurrently operating to their conductivity states at least all other controlled conduction devices of said current sinking means to which said remaining termination points of the harness under test are connected, and current sensing means for sensing current flow from said current source during open circuit and short circuit tests for providing an open circuit indicator signal for a particular individual circuit under open circuit test if there is no current flow during open circuit test and for providing a short circuit indicator signal for a particular individual circuit under short circuit test if there is current flow during short circuit test.

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