Z-Axis Crashing Into Bed


I recently installed the 4.0.6 build in an attempt to get my BLTouch Smart V3.1 to work. I have checked the connections and it seems the BLTouch works when I self test, probe up, down. It is a solid red when I start it up, however, I cannot level because the printer will no longer home the Z-axis correctly.

The Bltouch is confirmed genuine.

Aldi Balco Touchscreen Belgium
LCD: 4.0.6
Mainboard 4.0.6
Build: 200308182612
DGUS: 2.2
Marlin: 1.1.9
Bltouch V3.1

Also something I noticed was the bltouch sensor in the top bar of the lcd screen is grey and not orange as I see in a lot of your screenshots. I haven’t been able to figure out what that means.

Any help is appreciated.

First to bo sure:

  • Which version of the motherboard do you have (it is written on it)?
  • Which binary have you flashed for the motherboard (its full name)?
  • Which support have you used for the BLTouch?

This does test only the power (red, black, brown cables) and the servo pin (orange one) but not the white wire.

Yes this is expected in your case. The orange icon means that the mesh leveling compensation is active. In your case it is not since you do not have a mesh (you were not able to do at least one automatic bed leveling).

This problem (z stop not working) is often caused by two issues:

  • The white wire (sometimes the black one) is not wired properly. This wire is far more critical than the 4 other ones and a bad contact can interfere with the BLTouch
  • The distance between the tip of the BLTouch and the tip of the nozzle is not good (too small or too big).

It can help if you post here some pictures of your setup (soldering on the motherboard, BLTouch on your printer, …)

Forgot a common issue:

  • bad contact at the level of the dupont connectors.

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