HMS 0300-0800-0001-0002: Motor-Z short circuit
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HMS 0300-0800-0001-0002 means a Z motor is pulling more current than its winding resistance should allow. That is a short: turns of the coil touching each other, or a winding shorted to the motor can. The printer stops on purpose, because a shorted winding draws current the driver cannot survive for long.
Affected machines: A2L and P2S. The Z motors carry the bed, run warm on long prints, and stall hard against a crash rather than slipping. Those three things between them explain most Z winding failures.
Where to buy
Confirming the short before you order
A short shows up two ways on a meter. One coil pair reads noticeably lower than its twin, because part of the winding has been bypassed. Or there is continuity between a coil pin and the motor body, which means the insulation has failed to the can. Either reading is conclusive.
What is not conclusive is the error alone. A pinched cable can short two phases together and produce the same message, so look along the loom where it flexes before deciding the motor is finished. A crushed cable is far cheaper to fix than a motor.
Bed stops moving and the printer reports a Motor-Z short circuit, sometimes after a crash
Shorted stepper winding, occasionally a pinched motor cable
- Power off at the wall and let the bed settle on its stops before working underneath.
- Inspect the Z motor cable along its full run, especially where it enters the drag chain.
- Unplug the motor and measure resistance across both coil pairs. A pair reading clearly lower than its twin confirms a short.
- Measure from each pin to the motor body. Any continuity at all means the winding has shorted to the can.
- Fit the correct replacement for your model, keeping the coupler at the original height on the lead screw.
- Re-level the bed, then run a full Z homing cycle before starting a print.
Do not clear the code and try again to see if it holds. The protection tripped for a reason, and repeatedly energising a shorted winding is how a motor fault becomes a driver fault on the mainboard.
The other Z motor faults are Motor-Z open circuit and abnormal Motor-Z resistance. Our page on the lead screw covers the mechanism it drives, and the troubleshooting index covers the rest.
HMS 0300-0800-0001-0002 FAQ
Can a short damage the mainboard?
It can, which is why the printer stops rather than retries. Clearing and rerunning is the risky move here.
How do I tell a shorted motor from a pinched cable?
Measure at the motor connector. If the motor alone reads healthy, the fault is in the cable between it and the board.
Do I need to re-level after replacing it?
Yes. Any work on a Z motor or coupler moves the reference the mesh was built against.
Are the A2L and P2S motors interchangeable?
No. They are different parts, so order by model rather than by appearance.
LayerWalker
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