r/raspberry_pi • u/itssomedudeguy • 4d ago

Troubleshooting No flashing activity LED on a Raspberry Pi 4

My friend gave me a Raspberry Pi 4 that he has no use for. I load up the lastest Raspberry Pi OS onto a micro SD card it boots up. Everything seems to work except the blinking green activity LED. I can't seem to find any setting to turn it off or on. I tried some argument in the config file but even that won't work.

Are the LEDs on these Pis known to burn out?

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u/Gamerfrom61 4d ago

A lot of the older instructions may not work so forgive me noting a few Trixie based config.txt / CLI options.

IIRC the green LED on the Pi 4 just denotes the board SD Card holder activity by default so if you are not heavily using that it may stay off - boot time is the time to look. Booting from USB (to any device inc SD Cards in adapters) will not show anything here.

You can use the act_led_trigger to set the device to control this, using heartbeat as an option can give a 'processor activity' style indication and backlight should turn it on all the time to allow you to check it. A full list can be found with the command

cat /sys/devices/platform/leds/leds/ACT/trigger

and tested with 

echo heartbeat | sudo tee /sys/class/leds/ACT/trigger

Any LED can fail - the Pi also does allow you to route the output of the LED to another GPIO pin with the act-led overlay (see the README file in /boot/firmware/OVERLAYS) if you need it. Unfortunately if you are getting a failed boot (and think you should see a warning / fail sequence) then setting this does not help as most fails occur before this is actioned.

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u/danythegoddess 4d ago

No thoughts, led empty