Firmware crashes when extrude with heater OFF

Hi there,
I’ve got a need to extrude filament with heater being OFF but whenever I try to do so I get the following:

“Max31865 Overvoltage or undervoltage fault
Once the underlying issue is corrected, use the
“FIRMWARE_RESTART” command to reset the firmware, reload the
config, and restart the host software.
Printer is shutdown”

In order to extrude filament I use the following command:
G1 E100 F300
I set both min_temp: 10 and min_temp: 10 to minimum in the extruder config section
and max_extrude_only_distance is set to 500.0 so it should work but it won’t. The extruder starts moving filament but then the firmware crashes immediately.

My extruder config is show down below:

[extruder]
step_pin: PE2
dir_pin: PE3
enable_pin: !PD4
##	Update value below when you perform extruder calibration
##	If you ask for 100mm of filament, but in reality it is 98mm:
##	rotation_distance = <previous_rotation_distance> * <actual_extrude_distance> / 100
##  22.6789511 is a good starting point
rotation_distance: 22.6789511	#Bondtech 5mm Drive Gears
##	Update Gear Ratio depending on your Extruder Type
##	Use 50:17 for Afterburner/Clockwork (BMG Gear Ratio)
##	Use 80:20 for M4, M3.1
gear_ratio: 50:17				#BMG Gear Ratio
microsteps: 16
full_steps_per_rotation: 200	#200 for 1.8 degree, 400 for 0.9 degree
nozzle_diameter: 0.500
filament_diameter: 1.75
heater_pin: PA2
##	Validate the following thermistor type to make sure it is correct
sensor_type: MAX31865   #ATC Semitec 104GT-2
sensor_pin: PA15        #PF4
# spi_bus: 3
spi_speed: 4000000
spi_software_sclk_pin: PB3
spi_software_mosi_pin: PB5
spi_software_miso_pin: PB4
rtd_nominal_r: 100
rtd_reference_r: 400
rtd_num_of_wires: 2
rtd_use_50Hz_filter: True
min_temp: 10
max_temp: 270
max_power: 1.0
min_extrude_temp: 10
control = pid
pid_kp = 16.716
pid_ki = 1.211
pid_kd = 57.671
#control = pid
#pid_kp = 26.213
#pid_ki = 1.304
#pid_kd = 131.721
##	Try to keep pressure_advance below 1.0
pressure_advance: 0.05
##	Default is 0.040, leave stock
pressure_advance_smooth_time: 0.040
max_extrude_only_distance: 500.0

Is this a bug?
Thanks.

Sineos: Edit formatting

Does the MAX31865 reliably work for regular printing? The error message points to a hardware issue with the MAX31865, e.g. cabling, SPI settings etc.

For further diagnose, please post your klippy.log file.

Hi, thanks for your response.
I’ve performed comprehensive troubleshooting on my printer and found out that the problem is caused by the wiring loom dedicated to the extruder stepper motor. Both the pinout and continuity of it are OK and there are no shorts in between the neighbor wires as well but whichever stepper motor port it’s plugged to it crashes the firmware as soon as some motion command sent for that particular port. The firmware shuts down even if just the bare wire loom plugged to the controller with nothing on its other end. All that looks quite strange but needs to be attended anyway. I can definitely say that the issue I’m experiencing has nothing to do with MAXMAX31865 interface as the printer can successfully perform hot end PID auto calibration procedure. So the message I get about "MAXMAX31865 overvoltage/undervoltage seems to be irrelevant.

klippy.log (259.8 KB)

I have the same issue. I buyed without thinking about why the Octopus Pro and later i thinked for my self, i will use the benefit with more voltage at TMC5160 and more accurately hotend heating. But i readed your post to late. :slight_smile:
If anybode searching this issue with the MAX31865 and overvolting or undervoltin or temperature problems when the print want to start.
Dont spend time to fix it with editing .conf over and over. Change to NTC or, if you are fighter like me, change your cables to any professional shielded. I will change the Extruder Motor and the PT1000 to UNITRONIC FD CP (TP) plus 2x2x0,25mm² AWG24 AD 7,0mm and UNITRONIC FD CP (TP) plus 1x2x0,25mm² AWG24 AD 4,9mm. If it next week working or not, i will edit this comment.

Hi!
Did you get it to work?=)