Testing actuators: motors, solenoids and valves

CORE TEACHING Actuator power; ground; switched ground/high side; PWM; solenoids; DC motors; coils; flyback. Add DC motor construction basics: armature, brushes, commutator, magnetic field, reversing polarity, stall current, mechanical loading and how current ramp patterns reveal motor condition. PRACTICAL DEMONSTRATIONS AND TESTS Command actuator with scan tool; measure power/ground; current draw; resistance when appropriate; direct test only with known pinout/spec. Reverse a small DC motor safely; clamp current while free-running and while mechanically loaded. ADVANCED / SCAN TOOL LAYER Scope PWM command and current ramp; compare commanded percentage to actual waveform. KEY DIAGNOSTIC QUESTIONS Is command present? Is supply present? Can current flow? Does actuator physically respond? MUST-COVER CHECKPOINTS Start with the complaint; draw the circuit; identify expected inputs/outputs; perform physical tests; interpret evidence; prove the failed section; retest after repair.

ECU commands a component ON, but nothing moves. Is the ECU bad, the wiring bad, or the actuator dead?

Builds on

Lesson 25: Position sensors and plausibility

Feeds into

Lesson 27: Electric windows from switch to motor

1. 18Power, ground and signal — the universal sensor pattern
2. 19Testing a three-wire sensor
3. 20Two-wire temperature and resistive sensors
4. 21Hall-effect cam and crank sensors
5. 22Inductive sensors and AC signals
6. 23Pressure sensors — MAP, rail and A/C
7. 24Temperature sensors in real diagnosis
8. 25Position sensors and plausibility
9. 26Testing actuators: motors, solenoids and valves