HMS 0500-0300-0001-0007: Toolhead Expansion Module Fault
LayerWalker is a participant in the Amazon Services LLC Associates Program. We may earn a commission when you buy through links on our site, at no extra cost to you.
HMS 0500-0300-0001-0007 means the toolhead expansion module is malfunctioning, and it asks you to power off, inspect the wiring connections, and restart. Most codes in this family stop at “restart”. This one names wiring, which is a much better instruction than it looks.
The expansion module is what the extra toolhead hardware hangs off, so its wiring sits in the most-flexed part of the machine.
Where to buy
Shrink the repair properly, do not tape it
A variable-temperature heat gun shrinks tubing evenly without scorching the insulation next to it. A lighter does the job badly and leaves a joint that fails again in a warm chamber.
Give anything you remove somewhere safe
Resealable anti-static bags keep a module you have unplugged from collecting a charge on the bench. Static damage does not show itself while you are working; it shows itself a fortnight later as the same code.
Use tape that survives the chamber
Ordinary PVC tape unwinds at chamber temperatures and leaves adhesive on the loom. High-temperature fiberglass or glass-cloth tape stays put, which is the only kind worth using inside a heated enclosure.
Then inspect in the order the message implies
Power off first, look second, restart third. Inspecting a live machine is how a wiring fault becomes a short.
How HMS 0500-0300-0001-0007 differs from a plain toolhead fault
The toolhead itself reports HMS 0500-0300-0001-0002 and only asks for a restart. The expansion module gets the wiring instruction, so the two are worth telling apart.
When the motion controller is named instead
A controller fault is HMS 0500-0300-0001-000C, which also mentions checking the connection. The assembly it all drives is covered in the hotend guide and the machine in the Bambu Lab H2D.
HMS 0500-0300-0001-0007 FAQ
What is the expansion module?
The board the extra toolhead hardware connects through.
Why does it say inspect wiring?
Because its loom is in the most-flexed part of the machine.
Can I just restart and carry on?
You can, but the message asked you to look. Look.
Which tape should I use in there?
Glass-cloth or fiberglass. PVC unwinds when hot.
LayerWalker
Print defect diagnosis, calibration procedures and parts that actually fit. Corrections welcome through the contact page.
