So this problem came back after a couple of weeks and has been repeating itself. I keep replacing the relay with a different unit and the windows/seats start working again, but fail after a while.

Also to note, the power seats have completely failed, they do not even operate when the door is open. Windshield wiper does not operate as well.

Is there something else to check that might be causing this? The fuses are fine, they don't blow out. I've tried moving the relay around while holding the window controls up to find a loose terminal, but found nothing.

Is there a way to test the relay itself to find out if the relays are going bad or something else in the circuit is going bad?