How do you test a.i.v. solenoid on 1991 d21?

To test the A.I.V. (Air Intake Valve) solenoid on a 1991 Nissan D21, first, locate the solenoid near the intake manifold. Use a multimeter to check for continuity by disconnecting the electrical connector and measuring resistance across the solenoid terminals; a reading between 20-30 ohms typically indicates it's functioning correctly. Next, apply 12 volts directly to the solenoid to see if it actuates; you should hear a clicking sound if it's operational. If there are no clicks or continuity issues, the solenoid may need to be replaced.