# BLTouch 3.1 self tests, lights up, but doesn't respond **URL:** \ **Category:** General Discussion\ **Created:** [October 13, 2023, 12:37am UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949 "2023-10-13T00:37:02Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![hekis4](https://avatars.discourse-cdn.com/v4/letter/h/eada6e/32.png) [@hekis4](https://klipper.discourse.group/u/hekis4)\ **Post date:** [October 13, 2023, 12:37am UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/1 "2023-10-13T00:37:02Z")
### Basic Information: Printer Model: Artillery Sidewinder X2 with genuine BLTouch 3.1 MCU / Printerboard: Artillery Ruby 1.2 / stm32f401xc [klippy.log](https://klipper.discourse.group/uploads/short-url/cfsXZJiS0qxV4fh2Z1yB1JpBJXb.log) (127.2 KB) I have just upgraded the stock (read: trash) probe on my Artillery Siderwinder X2 to a genuine BLTouch 3.1. The new and old sensors are compatible pin for pin (except for a unique ground on the stock vs. two on the bltouch, I just joined the two grounds and replaced the connector). The new BLTouch has good electrical connections (tested by multimeter) does self-test when I power on the printer (extends and retracts twice, LED is fixed red, LED shuts off when extended), but it will not respond to commands (no movement, no message in console on any BLTOUCH\_DEBUG command) and shows up as triggered permanently to QUERY\_PROBE, even when extended by hand. G28 gives me “BLTouch failed to raise probe”. I have tried it with and without the sensor pin pull-up and with/without probe\_with\_touch\_mode, and tried running BLTOUCH\_DEBUG COMMAND=touch\_mode, but no luck. Any ideas on what may be causing this ? For reference: ```auto [bltouch] sensor_pin: ^PC2 control_pin: PC3 x_offset:27.25 y_offset:-12.8 #z_offset: 1.0 probe_with_touch_mode: True samples: 5 samples_tolerance: 0.050 samples_tolerance_retries: 3 speed: 1 ``` ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [October 13, 2023, 5:37am UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/2 "2023-10-13T05:37:07Z")
> [@hekis4](#): > > (except for a unique ground on the stock vs. two on the bltouch, I just joined the two grounds and replaced the connector) I’m not sure that this is a good idea (although I never tried) A lot of switching of the printer boards is done “on the low” side, this means that supply voltage is kept stable but actually GND is switched ---
**Author:** ![hekis4](https://avatars.discourse-cdn.com/v4/letter/h/eada6e/32.png) [@hekis4](https://klipper.discourse.group/u/hekis4)\ **Post date:** [October 13, 2023, 7:53am UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/3 "2023-10-13T07:53:03Z")
You mean, some boards pull up the ground instead of pulling down the signal ? I’m a bit skeptical of this, wouldn’t you need to specify which pin uses which ground ? And on the old probe that only had one ground to begin with, that would shut down the entire thing since you’d get 0V between +5V and GND… I’ll test this when I get home though, I really hoped I wouldn’t have to run wires all the way from the board but oh well. ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [October 13, 2023, 2:55pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/4 "2023-10-13T14:55:36Z")
[quote=“Sineos, post:2, topic:10949, full:true”] > [@hekis4](#): > > A lot of switching of the printer boards is done “on the low” side, this means that supply voltage is kept stable but actually GND is switched I have to agree with @hekis4 on this - I don’t believe this is true. Unfortunately, the BL Touch’s schematics aren’t published, but when I look at main controller board schematics, I typically see something like below where the two grounds are tied together (this is taken from the Octopus schematic which I currently have up): ![image](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/9/953e9e47cc2da0c0dd9300ad8577eac59f73bab8.png) So, I think shorting the two ground wires together at the BL Touch should be the same as having the same ground connection at the main controller board. From your description, it sounds like there is a problem with the control pin. The power on self test is just that, it checks the hardware but doesn’t check the serial control connection. Are there schematics available for this board (I want to look at the pins you’ve selected) but I can’t find any. ---
**Author:** ![hekis4](https://avatars.discourse-cdn.com/v4/letter/h/eada6e/32.png) [@hekis4](https://klipper.discourse.group/u/hekis4)\ **Post date:** [October 13, 2023, 3:36pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/5 "2023-10-13T15:36:15Z")
I’m afraid there’s nothing official, the klipper config is community-made based on the stock Marlin config, and I just reused the pins (and reordered the wires on the BLTouch connector to match what was written [on the breakout board](https://fr.aliexpress.com/item/1005003803638598.html?spm=a2g0o.detail.0.0.676985efCRSokL&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40050.354490.0&scm_id=1007.40050.354490.0&scm-url=1007.40050.354490.0&pvid=eb9f0df5-e035-4b3e-a75d-baa3492e7b0e&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.40050.354490.0,pvid:eb9f0df5-e035-4b3e-a75d-baa3492e7b0e,tpp_buckets:668%232846%238108%231977&pdp_npi=4%40dis%21EUR%218.33%217.92%21%21%218.58%21%21%40211b61b016972112154601950ed332%2112000027222117094%21rec%21FR%214184632828%21). Apparently someone reverse engineered the mainboard and got this: [Reddit - Dive into anything](https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fh87re4wrbrd91.png) Any idea on how I could check the control pin ? I have a spare arduino or rpi that I could probably fashion as a crude logic analyzer if push comes to shove. ---
**Author:** ![hcet14](https://avatars.discourse-cdn.com/v4/letter/h/ecd19e/32.png) [@hcet14](https://klipper.discourse.group/u/hcet14)\ **Post date:** [October 13, 2023, 3:49pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/6 "2023-10-13T15:49:50Z")
Found that on my HDD and don’t know where I found it! [BLTouchGuideV31.pdf](https://klipper.discourse.group/uploads/short-url/hTuRpColDuRm0jdXMGuG8Od8hEr.pdf) (626.1 KB) Good luck, hcet14 ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [October 13, 2023, 4:12pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/7 "2023-10-13T16:12:54Z")
> [@hcet14](#): > > Found that on my HDD and don’t know where I found it! > Good luck, hcet14 Thanx, but that’s not the schematic. It provides wiring information but I’d like to see how grounding is done between the power/control(servo)/gnd pins and the probe/gnd pins. ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [October 13, 2023, 4:27pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/8 "2023-10-13T16:27:13Z")
> [@hekis4](#): > > I’m afraid there’s nothing official, the klipper config is community-made based on the stock Marlin config, and I just reused the pins (and reordered the wires on the BLTouch connector to match what was written [on the breakout board](https://fr.aliexpress.com/item/1005003803638598.html?spm=a2g0o.detail.0.0.676985efCRSokL&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40050.354490.0&scm_id=1007.40050.354490.0&scm-url=1007.40050.354490.0&pvid=eb9f0df5-e035-4b3e-a75d-baa3492e7b0e&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.40050.354490.0,pvid:eb9f0df5-e035-4b3e-a75d-baa3492e7b0e,tpp_buckets:668%232846%238108%231977&pdp_npi=4%40dis%21EUR%218.33%217.92%21%21%218.58%21%21%40211b61b016972112154601950ed332%2112000027222117094%21rec%21FR%214184632828%21). Apparently someone reverse engineered the mainboard and got this: [Reddit - Dive into anything](https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fh87re4wrbrd91.png) Thanx for these. > [@hekis4](#): > > Any idea on how I could check the control pin ? I have a spare arduino or rpi that I could probably fashion as a crude logic analyzer if push comes to shove. The ideal would be to put an oscilloscope on the line. Have you checked the electrical connection from the Artillery board to the BL Touch? You should be able to probe the top of the BL Touch connector to see if the connection is good. Could you recheck all your wiring with a DVM along with the wiring states? Looking back at the datasheet that @hcet14 posted, it looks like the Control line is high when it’s not in use - could you confirm that (sorry, I don’t have a printer right now that uses a BL Touch so that I can’t compare on my own). ---
**Author:** ![hcet14](https://avatars.discourse-cdn.com/v4/letter/h/ecd19e/32.png) [@hcet14](https://klipper.discourse.group/u/hcet14)\ **Post date:** [October 13, 2023, 5:04pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/9 "2023-10-13T17:04:26Z")
> [@mykepredko](#): > > Thanx, but that’s not the schematic. It provides wiring information but I’d like to see how grounding is done between the power/control(servo)/gnd pins and the probe/gnd pins. I think there are no schematics ever published in the www and I was looking very hard years back. Usually I don’t start with new components without schematics. This was an exception. But that and a scope should be good. ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [October 13, 2023, 5:31pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/10 "2023-10-13T17:31:34Z")
> [@hcet14](#): > > Usually I don’t start with new components without schematics. Good rule to follow - I just wish manufacturers recognized that schematics are often required to figure out problems. ---
**Author:** ![hekis4](https://avatars.discourse-cdn.com/v4/letter/h/eada6e/32.png) [@hekis4](https://klipper.discourse.group/u/hekis4)\ **Post date:** [October 15, 2023, 6:35pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/11 "2023-10-15T18:35:54Z")
I found the issue, usual IT10T error code. Turns out the breakout board has a “probe” and a “servo” pin. I assumed the “servo” pin was the control pin and the “probe” was the ZMin, right ? Wrong, it’s the other way around. I tried switching sensor\_pin and control\_pin in the config and it is now working as expected. Thanks for your help, sorry about the waste of time 😕 ---
**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\ **Post date:** [October 15, 2023, 7:37pm UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/12 "2023-10-15T19:37:23Z")
Glad you got it working. It’s not a waste of time as what you found here could help somebody in the future. ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\ **Post date:** [November 15, 2023, 5:38am UTC](https://klipper.discourse.group/t/bltouch-3-1-self-tests-lights-up-but-doesnt-respond/10949/13 "2023-11-15T05:38:19Z")
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