The Open Collector Output means that when it is enabled, the output pin acts as the ground (or negative). When it is not enabled, the output pin is acting as a open circuit.

The output can be used to control devices such as horns for alert, light bulbs, and etc. Some other features could be using the output to achieve. One of the examples is the immobilization function.

The immobilization could be achieved by using relay and the output. First, you need to decide which power component in the vehicle you want to cut the power from. One of the possible components would be the fuel pump. In such case, you could connect the rely switch to the power cord of the fuel pump and use one output to control the relay switch operation.