| 摘要 |
A sensor circuit detects whether an electrical connection exists between a tractor portion and a trailer portion of a tractor/trailer vehicle. The circuit includes a first chassis electrical ground in the tractor portion and a second vehicle chassis ground in the trailer portion. A first electrical conductor, such as a wire in an umbilical cable, is coupled to the first chassis electrical ground, preferably through a tractor appliance circuit, such as a turn indicator light circuit in the tractor portion. A second electrical conductor, such as a contact in a connector on the trailer portion which mates with the umbilical cable, is operable to electrically connect to and disconnect from the first electrical conductor. The circuit includes a detection circuit for providing an indication signal based upon whether an electrical connection exists between the first electrical conductor and the second electrical conductor. 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 trailer appliance circuit, such as a turn indicator light circuit in the trailer portion. 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, where the voltage level at the anode of the diode is dependent at least in part upon whether an electrical connection exists between the first electrical conductor and the second electrical conductor.
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