The easiest way is certainly to unplug the control and place an ammeter clamp on the power wire that goes to the load. On the control, you apply the required voltage in DC with a battery or an independent cell, or in AC with a power supply independent of the installation, the voltage sources having been checked beforehand. If you have a current without the control present, the relay is short-circuited, and if you have no output current while the control is applied, the relay does not work..