Abstract: Vehicle parking brake warning systems are disclosed herein. In one implementation, a vehicle parking brake warning system may include a relay coupled to an operator warning system. The relay including a relay switch and a coil, the relay switch conductively couple the operator warning system to ground when closed, and the coil to cause the relay switch to open when an electrical current is flowing through the coil, the coil coupled to a first coil node and a second coil node. A brake status switch that couples the first coil node to a voltage source when closed. A driver status switch that couples the second coil node to ground when closed. And a capacitor coupled to the first coil node and the second coil node.

Abstract: Circuits for providing to an operator warning interfaced system of a transportation vehicle a conductive path to ground or voltage source are described herein. The operator warning interface system, when provided a conductive path to ground or voltage source, may generate an audio and/or visual alert that indicates that the parking brake of the transportation vehicle is disengaged. The circuits may include at least one switch that when integrated into a safety and warning system of a transportation vehicle and when closed provides a conductive path to ground or voltage source to an operator warning interface system of the transportation vehicle, where the switch closes when the parking brake of the transportation vehicle is disengaged. In some implementations, the circuits may further include a second switch that must be closed in order to provide the conductive path to ground or voltage source. The second switch may close when the vehicle ignition is turned off.