HMS 1A00-3300-0001-0041: Rack Position Sensor Is Short-Circuit
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HMS 1A00-3300-0001-0041 means the sensor that reports where the hotend rack sits reads as short-circuit, and Bambu asks you to reconnect the sensor cable or replace the sensor. Two things narrow this: the 3300 prefix means the rack rather than the toolhead, and short rather than open means damaged insulation rather than a loose plug.
Those two facts between them tell you which cable to inspect and what to look for on it.
Where to buy
The rack end, not the toolhead
The toolhead has its own presence sensor with its own codes under the 3000 prefix. This one is at the rack, which means a different connector in a different place, and it is disturbed whenever the rack is removed or refitted rather than on every print. Start there, and the setup step that follows a refit is HMS 1A00-1200-0002-0010.
Short points at insulation, not connectors
An open circuit is usually a plug that has worked loose. A short is two conductors touching, which happens where a cable is pinched by a frame member, chafed by movement, or trapped during reassembly. Follow the run and look at the places where it changes direction or passes something hard.
Check the connector for a bent pin
A pin pushed sideways during reseating bridges to its neighbour and reads as a short with no visible damage along the cable at all. Unseat the connector and look into it with a light before you condemn the wiring.
Confirm with a meter
Continuity across the circuit separates a shorted cable from a failed sensor, which decides what to order. The same method applied to other printer sensing is in 3D printer thermistors. Guessing here buys a part you did not need.
How HMS 1A00-3300-0001-0041 differs from its two neighbours
The open-circuit version of this same sensor is HMS 1A00-3300-0001-0040, where reseating clears most cases. The short-circuit version of the toolhead sensor is HMS 1A00-3000-0001-0041. Prefix tells you the place and the last digit tells you the fault type.
HMS 1A00-3300-0001-0041 FAQ
Can I print with it?
Single-tool, usually. Swapping and rack calibration both depend on position.
Did refitting the rack cause it?
Very likely. A cable trapped during reassembly is the classic origin of a short.
Will reseating help?
Less often than with the open version, but it is free and takes a minute.
Which part do I order?
Whichever the continuity test implicates, and not before you have run it.
LayerWalker
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