The video below shows how to test a stepper motor without using any multimeter , all you need is just a led.
CONCEPT: In any motor when electrical energy is converted into mechanical energy. So if we provide mechanical energy then output must be electrical energy.
Not only in case of just stepper motor but for a simple DC motor also this works fine.
Watch the video below to Know how to test a Stepper motor using a led in a simple way, without using any Multimeter
CONCEPT: "In a Stepper motor or any motor (DC) Electric energy is converted into Mechanical energy (rotation of motor shaft). Hence if we are providing mechanical Across Stepper motor Shaft then It must again further generate electric energy . This is called law of conservation of energy "Energy cant be created or destroyed it just transforms from one form to another" Or 1st law of thermodynamics , hence this results in glowing of led connected across terminals of Stepper motor shaft when it is provided with mechanical energy"