I’m using relay A to connect to a dpdt toggle that is also allowing power/signal input from the reverse lights on my vehicle. The other half of the switch in this position is wired to the com port on the wireless switch (202u, relay A). The 202u will be powered on and I’ve jumpered power to the NO port on relay A. If my vehicle is put in reverse, power from its signal wire can/will backfeed across my toggle switch signal wire (which energizes a separate relay controlling my backup lights) to the com port of the wireless relay (202u port A). It is 12v power, will this damage the 202u if relay A is not energized (power coming INTO the com port but nowhere for it to go since relay is not energized)?
As far as I understand, it shouldn’t be problem.
Actually for relay operation, it is perfectly normal that power coming into com but go nowhere (when relay is not energized).
Relay will usually be damaged, only when the carrying current/voltage is out of specs, for example, exceeding 10a @12vdc for resistive load. (the contacts will melt).