Hi, I bought a Fanshim over the weekend. The fan is on constantly, but there is no LED activity on the shim and the button does not appear to work.
The only interfaces enabled are I2C and Serial Console.
I just ran i2cdetect -y 1 and there is nothing showing on the map.
The good news is that so far the temperature has not gone above 40.
I tried bending the pins slightly but that didn’t do anything.


The fan shim doesn’t use i2c.

You may have to turn of the serial console off though as it uses the UART GPIO pins?
Did you enable the Serial Console manually?

You ran the installer, and installed the daemon?

I have a fan shim on the way, I should have it any day now. I won’t be able to play around with it until that happens though.

Hi, thanks for the info.
I followed the instructions on the Pimoroni Learn page.
When I looked at page that shows BCM 3 (wake) as an I2C pin so I assumed I2C needed to be on.
I have taken the fan off and tried a Sense Hat. That worked OK and showed up on I2Cdetect. It also got the heat up to 60+ 😂

I put the fanshim back on and the LED came on and it is now responding to the temperature setting.

I think it may be simply down to poor connections.

Thanks again for the assistance.



GPIO 3, Pin 5, can be used to turn the Pi on and off. If you shut down and leave the power supply connected, momentarily grounding Pin 5 will make the Pi Boot up. Except a Pi 4B, you have to flash a new bootloader to get that functionality back. And a config.txt edit “dtoverlay=gpio-shutdown” will have your Pi do a proper shutdown when grounding Pin 5. Its a secondary function of that Pin not associated with i2c.
I do believe the Fan Shim button can make use of this and be used to turn the Pi on and off.

I plan on soldering my Fan Shim to a header to avoid any issues like this. Thats the plan anyway. I’ll test fit it first to see if I get the spacing I want before soldering it. My plan is to mount the fan under its holder to lower it to compensate for my header raising it.

Thanks for the info. Good luck with mounting the fan underneath. I think you will have to cut some plastic away

I have a dremel tool to modify it if need be. ;)

Fan shim just arrived in the mail.
It won’t fit on the GPIO with the heatsink in place. Not and be anywhere near a reliable connection, it would be right at the end of the pins.
I put a booster header on the GPIO and plugged it into that. Spacing looks OK to me with the fan in the stock mounting position. I haven’t soldered anything yet. Just going to let it run and see how it works out. Software is installed and the daemon is setup.
The button will do a shutdown if its running, and a boot up if I leave it powered up. Fan stays on constant though after the Pi shuts down which is a bit of a bummer. I’ve ben told that is because I flashed a different boot loader into the firmware.
LED appears to be working too.
Its “was” sitting in the hot sun, but now its in the shade, Might be a while before it hits 65c, its at 50c right now.

Other than the fan not turning off when the Pi shuts down, everything appears to be working as advertised. I saw the LED go yellow, then orange, then Red. Then the fan turned on and ran until the temp went back down to 55c. Led then went green again.

I guess the next step is to go back to the stock boot loader. I think that going to break the on off button functionality. I guessing it will shutdown but won’t boot up when the button is pressed.

I haven’t noticed what the LEDs is doing to be honest. The fan keeps the Pi very cool. With the fan on I haven’t had the temperature above 55

I just turned that Pi on. I made a small modification to the fan, trimmed one small bit of plastic out from one of the mounting tabs. My fan is now mounted without the two nuts as spacers. I may have to double check it as it sounded like it was making a small noise when running while the Pi booted up. It was whisper quite when I first set it up.
It slowly climbs to 65, the fan turns on and about 20 seconds latter its down to 55 and the fan goes off. Wash rinse and repeat. ;)

EDIT: Fixed the noisy fan issue, The round shroud got bent slightly out of round. Must have happened while I was holding it and cutting the plastic with my exacto knife. I just pinched it a little and its quite again. The tip of one of the vanes was rubbing against the one side of the shroud.

Here is what I “think” is going on. The Fan Control pin is pulled Low to turn the fan off. Thats done so the fan runs even with no software installed. It just runs continuously because the control pin is floating high.
On boot up, before the fan shim software starts running that pin is floating, so its effectively high. Fan is on.
Software loads and pulls that pin low, fan goes off. Until the temp hits the threshold to turn it on again.
Shut the Pi down and that pin goes back to floating High. fan turns on.

With the original eeprom code the +5V and 3.3V were turned off. The fan goes off as it doesn’t have any 5V. The Pi won’t boot up via GPIO 3 though.

With the new eeprom code the +5 and 3.3V stay on. The fan stays on as it now has 5V and the fan control pin is high. And the Pi will now boot up if your ground GPIO 3

Please, take a picture of the fanshim installed with booster header. I am curious to see how it looks like.

Carl / Finland

Will do. It will be latter on today. I have some stuff on the go right now. Will also have to go find my camera, lol.

This is the header I used

I plugged that into the Pi’s GPIO, then plugged the Fan Shim into that, then attached a Blinkt on top of the Fan Shim

Several pictures here in my OneDrive Public folder.!AjOYwiwlwDtpguoraJSPeVUp0HARbg?e=GSiKcy