| 摘要 |
A sensor circuit detects whether an electrical connection exists between the tractor and trailer of a tractor/trailer vehicle. The circuit includes a first chassis electrical ground in the tractor and a second chassis ground in the trailer. A first electrical conductor, such as a wire in an umbilical cable, is coupled to the first chassis electrical ground, preferably through a turn indicator light circuit in the tractor. A second electrical conductor, such as a connector on the trailer which mates with the umbilical cable, may be connected to and disconnected from the first electrical conductor. A detection circuit provides an indication signal to indicate whether an electrical connection exists between the first and second electrical conductors. The detection circuit includes a detection diode having an anode which is electrically connected to the second electrical conductor, where the anode has an anode voltage thereon. The diode has a cathode which is electrically coupled to the second vehicle chassis ground, preferably through a turn indicator light circuit in the trailer. The detection circuit also includes a biasing-current source for providing a forward biasing current to the anode of the diode. The detection circuit further includes a comparison circuit for providing an output signal indicative of a voltage level at the anode of the diode, which is dependent at least in part upon whether an electrical connection exists between the first and second electrical conductors.
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