Is the PR22-4 a low side switch? The device used is an N-channel FET, which is typically used for a low side switch. From tracing the PCB, the drain is connected to the terminal marked negative, and the source is connected to the terminal marked positive.
How do I tell which of your products are high side switches, and which are low side switches? Or, is it, you don’t offer any FET state high side switch products?