Actuators are critical components in modern vehicles, used across multiple systems to convert electrical commands into mechanical actions. These systems include the engine, air conditioning, anti-lock braking system (ABS), electronic controlled air suspension (ECAS), and dashboard displays. Examples of common actuators include throttle bodies, fuel injectors, ABS modulator valves, air blend doors for HVAC systems, suspension height control solenoids, and instrument panel gauges.

Actuator testing in vehicle diagnostics can involve direct verification of operation or simulation of various conditions, for example:

• ABS: an actuator test might involve cycling the solenoid valves in the hydraulic modulator to verify brake pressure modulation.
• H/V + A/C: tests may activate blend doors to confirm proper airflow direction and temperature regulation.
• ECAS: solenoids can be activated to raise or lower the suspension, simulating load conditions.
• Instruments panel: gauge motors, can be commanded to specific positions to confirm accurate readings, LED can be turned on

These tests provide immediate insight into whether an actuator is functioning or if issues like mechanical wear, electrical faults, or communication errors are present, enabling precise troubleshooting across various vehicle systems.