M17 turns on the printer's stepper motors.

The motors become energized and hold their position.
If the motors were switched off (e.g., by M18, M84, or after a timeout), you can use M17 to:

• Lock axes
• Enable movement
• Stabilize the print head
• Activate the extruder

Why is M17 important?

Because stepper motors only hold their position when they are switched on. When they are off:

• Axes can move freely
• The print head can slip
• The extruder cannot extrude

That's why M17 is essential for:

• Manual adjustments

Code

Activate all motors

M17

Activate Z-axis motor(s)

M17 Z

Important to know

M17 activates motors, but does not change the motor current.
Motors remain Active until:

• M18 or M84 is executed
• a timeout is reached
• the firmware automatically disables them
• When motors are active, they cannot be moved manually.
• On CoreXY printers, X/Y always activate both motors simultaneously.

Klipper

Klipper is internally mapped to SET_STEPPER_ENABLE.

RepRapFirmware

RepRapFirmware M17 activates motors; RRF uses M906/M913/M917 for power control.