Why does the flasher on a 1996 ford explorer hum when the blinkers are off but when the blinkers are on there is no humming sound?

The humming sound from the flasher on a 1996 Ford Explorer when the blinkers are off could be due to a failing flasher relay or a poor electrical connection, causing the relay to vibrate. When the blinkers are activated, the relay functions properly to create the blinking signal, which may eliminate the humming sound. Additionally, the load from the bulbs when the blinkers are on might dampen the vibrations that cause the hum. It's advisable to inspect the flasher relay and connections to resolve the issue.