Fan Stops Working TX2 J120 Jetpack 4.3

Here are some details about my hardware and build environment


I have the auvidea J120 Rev7 carrier board and have patched the firmware version 3 for Jetpack 4.3

I have the original fan installed on the board and it starts up and runs for a short period of time depending on how long it has been sitting without power connected to the board. The fan will sputter out and stop working and occasionally will give a few spins.

I previously had Jetpack 4.2 installed and firmware version 2.2 and the fan ran all the time at full speed, which from what I read on the forums is the only way the fan is supposed to be able to work on the J120 for all versions of Jetpack >=4.2

I compared these .dtsi files from the kernel_src files provided by auvidea in the firmware versions 2.2 and 3 to see if something changed to cause this issue but no changes were made to these files that other users have cited in other posts.

I am currently looking into trying to pull the GPIO for vdd_fan which is GPIO 244 according to this article from ridgerun.
See “Control Fan PWM (sysfs)” section

sudo su
cd /sys/class/gpio/
echo 244 > export
cd /sys/class/gpio/gpio244
echo out > direction ; cat direction

Im not yet sure what to echo to the GPIO in order to set the pwm period and duty cycle or if all I need to do is simply set the target_pwm to 255. Ill update this thread once I get more information but I was hoping someone with more experience could give me some guidance.

note that the usual suggestion “echo 255 > /sys/kernel/debug/tegra_fan/target_pwm” does not work and this filepath does not exist on the machine.

I am not really that experienced in interfacing with the GPIO using this approach but I would much rather prefer to have a CLI solution than disable the driver and make the changes to the .dtsi file as referenced in the same ridgerun documentation. Im trying to avoid needing to recompile the kernel and flashing the OS again…

Any suggestions are more than welcome!


Hi Alex,

Please refer to below topic to see if can help:

Unfortunately, the fix for the fan I originally posted last year for Jetpack 4.2.2 does not work with Jetpack 4.3.

@akrolic I am facing the exact same issue with the Auvidea J121 board along with Jetpack 4.3 and the Auvidea firmware.
Did you succeed with your idea to pull the GPIO and set the PWM period?

@mtbsteve I disabled the device driver in the device tree and recompiled the kernel following ridgerun’s guide. I tried to pull the GPIO but it did not work.

One thing I noticed is that when I have the TX2 on the Dev Board in jtop it shows that there is a fan available, whereas on the J120 it shows fan [off]. I didnt test with the fan on the devboard to see if it actually works or not, because I stripped the wiring and hooked it up to my arduino to verify it wasnt the fan failing. It works as it should on the arduino so for sure this is a problem Auvidea needs to address.

Right now I just have Jetpack 4.3 installed and I followed the generic steps for flashing the J120 firmware. I have hardwired 2 12V DC fans to my power distribution board as seen in the picture below. It can run full blast now!