BLTouch Not Deploying the Pin – Causes & Fixes

While there’s no dispute that installing a BLTouch to your 3D printer makes the bed leveling process much more convenient and reliable, it’s definitely possible to come across some problems that prevent the probe from working as intended and take all the convenience away, with the BLTouch not deploying the pin being one of the more common ones that many users face at some point.

In this guide, we will take you through the common issues that can prevent your BLTouch from deploying the pin as intended, along with the corresponding solution methods that will help you resolve the problem you’re facing as conveniently as possible.

BLTouch Not Deploying the Pin – Causes & Fixes

While noticing that the automatic bed leveling (or auto homing) process is failing due to the BLTouch not deploying the pin is pretty straightforward, finding out the root cause that leads to the occurrence of this problem is the challenging part due to the many possible factors involved.

Pin Stuck Inside the BLTouch Case

The most common cause behind the BLTouch not deploying its pin is the pin itself getting stuck within the BLTouch case for various reasons, as it’s a pretty sensitive component that can easily get affected, whether during usage or when you’re setting the BLTouch up for the first time.

Some of the most common factors that can create such a scenario are the BLTouch pin getting slightly bent and dust and dirt accumulating inside the BLTouch case and eventually preventing the pin from moving as intended, which, due to their hard-to-observe nature, at least from the outside, can make it challenging to find out where the problem is.

Regardless, the first step we recommend taking to rule this culprit out would be to unscrew the magnetic screw at the top of the BLTouch case, which will allow you to remove the pin from the BLTouch, and make it possible to access the inside of the case.

Next, you will need to confirm that the pin is entirely straight by carefully inspecting it, as even a slight bend that goes unnoticed can create a scenario where it becomes unable to move within the case while leading you to look for the problem elsewhere.

In a case where you are unsure whether the pin is straight or not after inspection, a method that can come in pretty handy is to place the pin inside without re-attaching the magnetic screw and to push it up from the bottom of the BLTouch with an object of your choice (refrain from using your finger to avoid getting the pin dirty), as this will allow you to see whether the pin can move freely without any resistance, which should be the case under normal circumstances.

If the pin is indeed bent, you can either straighten it with the help of some tweezers, preferably without applying too much force to avoid further damaging it or grab a replacement pin if the bending seems to be at a level you cannot fix, which should run much cheaper than replacing the BLTouch altogether.

Once you have a straight pin at hand, the next step we recommend taking is to clean both the pin and the inside of the BLTouch case with the help of some electronics cleaner (you can spray it inside the BLTouch case and on the pin itself since the liquid will evaporate in a few seconds), which will practically ensure that there isn’t any dust and dirt that can hamper the pin’s movement.

To be on the safe side before putting the BLTouch back together and back on your 3D printer, you can once more test the pin’s movement with the method we have mentioned earlier after the cleaning process, as being able to move it up and down manually without obstructions will effectively allow you to confirm that it’s not getting stuck in the case.

Finally, once you confirm that the pin can move freely within the BLTouch, our last recommendation is to put the BLTouch pin back inside with the help of some tweezers instead of picking it up with your hand, as this is the best way to ensure that you don’t end up transferring grease to the pin after you have just cleaned it.

Magnetic Screw Tightened Too Much

Another simple yet widely encountered problem that can prevent the BLTouch pin from deploying as intended is the magnetic screw, which is responsible for pulling the pin up and pushing it down, being overly tightened.

The closer the magnetic screw, and as a result, the magnetic field produced by it, gets to the BLTouch pin as a result of tightening, the stronger the electromagnetic force that pulls the pin up (which is how the BLTouch stows the pin) becomes, creating a scenario where the BLTouch becomes unable to release the pin due to the pull being way too strong.

Our primary recommendation to resolve this problem in the quickest way possible would be to loosen the magnetic screw slightly by turning it counter-clockwise and to attempt deploying the probe (you can use either the M401 G-code command on Marlin Firmware or your 3D printer’s LCD controller for the task) after each minor adjustment, which should allow you to find the exact spot where the pin deploys successfully without overly loosening the magnetic screw.

As loosening the magnetic screw way too much will create the opposite problem, where the BLTouch will not be able to stow the pin anymore due to the magnetic force generated by the screw not being strong enough to pull the pin upward due to the increased distance, minor adjustments & frequent testing is the key to avoid more problems down the road.

Incorrect / Damaged Wiring & Loose Connectors

Wiring and connector problems, whether it’s a wire connected to the wrong pin, a wire that’s damaged, or a connector that’s coming loose, can also be the culprit behind your BLTouch not being able to deploy its pin as intended.

As it’s rare for wiring issues to occur out of nowhere when your BLTouch has been working without issues for a while now, we can say that it’s a whole lot more likely for wiring-related problems to be the culprit if you set your BLTouch up for the very first time, or if you have recently opened up the mainboard cover of your 3D printer and made some modifications to the wiring.

Regardless, the first step we recommend to rule out wiring-related problems is to disconnect the BLTouch cable from both ends and to inspect both the wires and the connectors for any signs of damage, such as a bent/kinked wire or a wire that doesn’t sit tightly in the connector, and to replace the cable if you come across any such issue.

Next, refer to the wiring section on the BLTouch website and the TH3D BLTouch guides, where you can find handy information, such as pinout diagrams for the BLTouch and different mainboards, the ordering of the wires, and where the wires should connect based on the mainboard, which is the most reliable way to ensure that you’re connecting the wires to the correct pins on both the BLTouch and the mainboard, especially considering that getting the wiring down correctly can be a bit of a challenge based on the mainboard you’re using.

Additionally, we highly recommend paying close attention to the coloring of the wires when following the diagrams, comparing the order of the coloring with the cable you have, and refraining from assuming that wires are already correctly ordered (you can find more info about this on the documentation pages we have mentioned previously), as it can become necessary to change the ordering of the wires depending on the order of the pins on the mainboard you’re using.

Provided that your BLTouch is not deploying the pin despite being powered on, which technically indicates there should be no issues regarding the +5V and the GND wires, the connection you will specifically need to pay attention to is the wiring between the servo pin on the BLTouch and the servo pin on your mainboard, which is what’s responsible for stowing & deploying the probe.

Finally, ensure that the connectors sit tightly on both the BLTouch end and the mainboard end without any wiggle, as either connector sitting loosely on the pins will cause the connection to become unreliable, which can also contribute to the occurrence of the problem you’re facing.

Misconfigured Firmware

Since the firmware is fully responsible for controlling the BLTouch, whether deploying or stowing the pin, using firmware that’s not correctly configured for your 3D printer is another factor that can lead to your BLTouch becoming inoperational.

Taking into account that firmware configuration won’t change on its own and start creating issues out of nowhere, you should only consider misconfigured firmware as a possible culprit if you set your BLTouch up for the first time or if your BLTouch started having this problem right after you switched to a new firmware, and go through the other possible culprits before coming back to this one as a last resort if these conditions don’t apply to you.

The most straightforward way to ensure that you won’t have firmware-related issues with your BLTouch is to flash the official BLTouch-enabled firmware for your 3D printer, which practically guarantees that the firmware is configured correctly for the BLTouch to work as intended, whether it’s the number of the servo pin or the status of the 5V mode.

For instance, for an Ender 3 V2 with a Creality V4.2.7 mainboard, you can find the correct firmware on the Ender 3 V2 section of the Creality website, where the firmware file is clearly labeled to let us know that it’s for usage with a V4.2.7 mainboard, and is BLTouch (and filament detection) ready.

ender 3 v2 bltouch firmware example


Since the firmware will have the configuration to use the pre-defined pin layout that’s created explicitly for the Creality V4.x.x series of boards in this case, where the number of the servo pin (PB0) in the firmware configuration correctly points to the pin where the BLTouch servo wire is (or at least should be) connected, firmware-related problems will practically be out of question regarding the deploying (and the stowing) of the BLtouch pin.

marlin mainboard config example

marlin servo pin config example


Even if you prefer to compile and use your own custom firmware, which is understandable due to most stock firmware not being great, finding out whether the problem is firmware-related or not by testing with official firmware first is still something we recommend doing, as this will allow you to find out whether you should be working to fix your firmware configuration, or looking for the problem elsewhere.

Defective / Damaged BLTouch

If everything else seems to be in order, whether it’s the wiring or the firmware configuration, the BLTouch itself being damaged or defective becomes a real possibility, and considering that it’s possible to find many community reports where this is the case, it’s not unlikely for this to be the culprit either.

In this case, the very first step we recommend taking is to verify that your BLTouch is genuine by inputting the serial number, which you can find printed right next to the QR code on the PCB, into the BLTouch Validation website, as there are so many BLTouch clones that are sold as genuine, and end up creating problems without seeing too much use.

Provided that your BLTouch probe is indeed genuine, you should come across a message that tells you so once you submit the serial number, such as in the example image you can see below.

bltouch genuine


As the owner of a genuine BLTouch, the best way to move forward in resolving the problem you’re experiencing would be to contact ANTCLABS (which is the company that produces the BLTouch), together with the details of the troubleshooting steps you have taken so far, as this will help them to point you in the right direction, or even replace your BLTouch if necessary.

On the other hand, if your BLTouch turns out to be a clone, whether, with no serial printed at all, or a serial that comes up invalid on the verification tool, our recommendation would be to discard the probe and purchase a new, genuine BLTouch instead from a reputable seller instead.

bltouch not genuine


Even though using a genuine BLTouch doesn’t guarantee that you won’t have problems by any means, it will certainly reduce the chance that you do and also make it possible to receive support from the manufacturer for any issue you may face, whereas a clone BLTouch has no actual brand behind it.

Defective / Damaged Mainboard

Even though it’s rare for this to be the case compared to everything else we have mentioned so far, it’s certainly not impossible for a mainboard-related issue to be causing the problem you’re experiencing, especially if you’ve gone through everything else on the list so far with no solution in sight.

While we can say that mainboard-related issues are more likely to be the source of the problem you’re experiencing if you have recently interacted with it in some way, whether it’s installing new hardware to your 3D printer, replacing a component, or switching some wiring, as you can accidentally cause a short circuit or damage a pin, it’s not exactly unheard of for a mainboard to malfunction out of nowhere either, whether due to it being defective all along, or being affected by a power surge.

As a malfunctioning mainboard preventing your BLTouch from working as intended is practically unfixable regardless of the reason (unless you have a high-level understanding of electronics and possess the necessary tools & parts for the task), you will need to replace the mainboard with a new one in this case, which, unfortunately, makes it the worst possible scenario you can come across out of everything we have discussed so far.

On the flip side, if you’re using a 3D printer with a mainboard that we can consider to be old and outdated, such as an Ender 3 with a Creality v1.1.x series mainboard, this can be a fantastic opportunity to upgrade your 3D printer’s mainboard with one that offers better functionality, such as a Creality v4.2.x series mainboard with silent stepper motor drivers, which can possibly allow you to take away some positives from an otherwise unfortunate event.

Conclusion

Now that you have a list of possible culprits that can cause your BLTouch pin not to deploy at hand, along with the corresponding solutions, it should hopefully be possible to resolve the error you’re facing in a swift manner and get back to enjoying the benefits that automatic bed leveling brings to your prints.

While it will definitely take some trial and error to find the root cause due to there being no way of knowing where the problem is without ruling each of the possible culprits out one by one, we can say that the more severe issues, such as the BLTouch itself or the mainboard being damaged, are usually on the rarer side.