Troubleshooting Stepper driver

Joshua_Cloete · March 3, 2026, 6:27am

Good day everyone,

I’m currently building my LowRider CNC using a Jackpot 3 Controller, and I’m running into an issue with the Z-min stepper motor (or possibly the stepper driver). The Z-min motor is completely unresponsive, while all other motors are working correctly.

What I’ve Tested So Far

The lead screw turns freely by hand when the machine is powered.
I plugged the Z-min stepper motor into the Z-max driver, and the motor worked correctly then.
I was asked to run and post the $SS output from the WebUI below this message for reference.

Thanks so much for your help — I really appreciate it!

$SS

**MSG:INFO**: FluidNC v3.9.9 https://github.com/bdring/FluidNC

**MSG:INFO**: Compiled with ESP32 SDK:v4.4.7-dirty

**MSG:INFO**: Local filesystem type is littlefs

**MSG:INFO**: Configuration file:config.yaml

**MSG:INFO**: Machine LowRider

**MSG:INFO**: Board Jackpot3 TMC2226

**MSG:INFO**: UART1 Tx:gpio.16 Rx:gpio.4 RTS:NO_PIN Baud:115200

**MSG:INFO**: I2SO BCK:gpio.22 WS:gpio.17 DATA:gpio.21Min Pulse:2us

**MSG:INFO**: SPI SCK:gpio.18 MOSI:gpio.23 MISO:gpio.19

**MSG:INFO**: SD Card cs_pin:gpio.5 detect:NO_PIN freq:20000000

**MSG:INFO**: Stepping:I2S_STATIC Pulse:2us Dsbl Delay:0us Dir Delay:1us Idle Delay:255ms

**MSG:INFO**: User Digital Output: 0 on Pin:gpio.26

**MSG:INFO**: User Digital Output: 1 on Pin:gpio.27

**MSG:INFO**: User Digital Output: 2 on Pin:gpio.0

**MSG:INFO**: User Digital Output: 3 on Pin:gpio.2

**MSG:INFO**: Axis count 3

**MSG:INFO**: Axis X (3.000,1223.000)

**MSG:INFO**: Motor0

**MSG:INFO**: tmc_2209 UART1 Addr:0 CS:NO_PIN Step:I2SO.2 Dir:I2SO.1 Disable:I2SO.0 R:0.110

**MSG:INFO**: Neg Limit gpio.25

**MSG:INFO**: Axis Y (3.000,2443.000)

**MSG:INFO**: Motor0

**MSG:INFO**: tmc_2209 UART1 Addr:1 CS:NO_PIN Step:I2SO.5 Dir:I2SO.4 Disable:I2SO.7 R:0.110

**MSG:INFO**: Neg Limit gpio.33

**MSG:INFO**: Motor1

**MSG:INFO**: tmc_2209 UART1 Addr:3 CS:I2SO.14 Step:I2SO.13 Dir:I2SO.12 Disable:I2SO.15 R:0.110

**MSG:INFO**: Neg Limit gpio.35

**MSG:INFO**: Axis Z (-147.000,3.000)

**MSG:INFO**: Motor0

**MSG:INFO**: tmc_2209 UART1 Addr:2 CS:NO_PIN Step:I2SO.10 Dir:I2SO.9 Disable:I2SO.8 R:0.110

**MSG:INFO**: Pos Limit gpio.32

**MSG:INFO**: Motor1

**MSG:INFO**: tmc_2209 UART1 Addr:3 CS:I2SO.19 Step:I2SO.18 Dir:I2SO.17 Disable:I2SO.16 R:0.110

**MSG:INFO**: Pos Limit gpio.34

**MSG:INFO**: X Axis driver test passed

**MSG:INFO**: Y Axis driver test passed

**MSG:INFO**: Y2 Axis driver test passed

**MSG:INFO**: Z Axis driver test passed

**MSG:INFO**: Z2 Axis driver test passed

**MSG:INFO**: Kinematic system: Cartesian

**MSG:INFO**: STA SSID is not set

**MSG:INFO**: AP SSID FluidNC IP 192.168.0.1 mask 255.255.255.0 channel 1

**MSG:INFO**: AP started

**MSG:INFO**: WiFi on

**MSG:INFO**: Captive Portal Started

**MSG:INFO**: HTTP started on port 80

**MSG:INFO**: Telnet started on port 23

**MSG:INFO**: Probe gpio.36:low

ok

vicious1 · March 3, 2026, 2:06pm

Thank you for such a solid post, I think you actually covered everything.

So it looks like we have a bad batch of drivers or uart chips in this batch of boards. I am actively working on it right now. The other possible issue here could be some debris or stray solder shorting a pin on one of those chips. From Your $SS the communication looks good to all drivers so it must not be the UART, hard to say. I hope to put a lot of time in to this today.

The fastest solution is to swap to the Z min to the empty C port.
edited----
Unzip and upload this config to your board, power down and move the Z min to the C port, when you power back on all should work as expected. If you ever need a 6th driver for any reason just let me know.

Joshua_Cloete · March 4, 2026, 8:17am

Thank you so much. Just uploaded and did some tests. Not quite fixed yet.
I used both z-stepper motors on all the z drivers and here is what I found:
Z0 - the lead screw remains loose while power is on
Z1 - works perfectly for both stepper motors
C - Z max motor works perfectly but the Z min motor is engaged but not turning.

I also noticed now that the Z min cable is slightly looser and wiggles around a bit easier.
Also the board feels a bit hotter wherever the z min cable is plugged in.

vicious1 · March 4, 2026, 1:57pm

On the board plug? The stepper wires come out really easily, with something sharp just bend up the little tab, then pull the wires out. Take a look at the connector real quick and see if any of the four are not like the rest.

I am getting a little lost of the situation. I think we need better separation of terms. Lets call the board ports, XYZABC, eg PortX. Then the actual Steppers something like Zmin Stepper, or Zmax Stepper.

z0 and z1 are not clear as to what you are referring to.

This sounds like a bad wire connection in your Stepper, either the plug or extension.

Joshua_Cloete · March 5, 2026, 7:21am

Okay great I’ll do that. I checked it again today that I can be sure on what is working and what is not.
And today the result is different.
PortZ - non responsive for both stepper motors. The lead screws turn freely with power.
PortB - both steppers stiffen but the leadscrew is not turning.
PortC - both steppers are turning correctly.

vicious1 · March 5, 2026, 2:15pm

Well crud, It is starting to sound like we got a bad batch of drivers.

I think we need to have you send it in.

Joshua_Cloete · March 5, 2026, 4:11pm

Aww shame man that is quite lame. Let me know how to do that.

Thanks Ryan.

vicious1 · March 6, 2026, 4:12pm

Okay sorry lets start this again.

vicious1 · March 6, 2026, 4:17pm

https://github.com/V1EngineeringInc/FluidNC_Configs/releases/download/2025_November_14/JP3_LR.zip If you go back to this file the stepper plugged into the “Z” port does not even energize (you can free spin it by hand while all the rest are not easily moved)?

Joshua_Cloete · March 6, 2026, 5:08pm

Yes I uploaded the file and the Z port does not energize.

vicious1 · March 6, 2026, 5:34pm

Sorry the previous driver was broken. making /testing a new one now.

vicious1 · March 6, 2026, 5:39pm

z_C_swap.zip (1.6 KB)

This works. I had z, B, and C all mixed up.

Joshua_Cloete · March 6, 2026, 6:01pm

Here is what I’ve got after uploading this file.
Zport - not energized (i can turm the leadscrew freely with my hand)
Bport - is energized but it does not turn the leadscrew when it should jog
Cport - works perfectly

vicious1 · March 6, 2026, 6:10pm

What about X and Y?

vicious1 · March 6, 2026, 6:13pm

So with the stock config port “B” works fine, if you put the swapped config on port “B” stops working?

vicious1 · March 6, 2026, 6:17pm

I am asking about port A because the multiplexer chip controls A, B, C. Somehow you have a bad driver and a bad multiplexer, that seems unlikely.

vicious1 · March 6, 2026, 6:22pm

Are you using a windows machine?

Joshua_Cloete · March 6, 2026, 6:32pm

X and Y work perfectly. (A-port also works perfectly)

PortB is energized but not turning for both configs.

Macbook

vicious1 · March 6, 2026, 6:41pm

Well being international makes this harder…Sorry. If you want to keep trying some more troubleshooting I have a couple more ideas.

For Mac, Release v3.9.9 · bdring/FluidNC · GitHub download the posix zip, unzip it, over USB run erase, then install_fs, then install_wifi. After that connect with the webinstaller and upload all the stock files again. See if that full deep erase helps, I am just concerned that you are showing two issues at once, that is not right. Make sure there is no debris on the board, the heat sinks are not touching anything.

Can you upload a picture of your board wired up please.

Joshua_Cloete · March 6, 2026, 6:49pm

I’m keen to hash it out now. Let me start and post as I manage to do the above steps