Okay, so my car vibrates when in drive and idling. I was told this could be caused by a non-functioning vacuum motor mount system. I unplugged the solenoid when the car was warmed up, and in drive (someone held the brake) and there was no change in vibration. How can I tell if the problem is with the mount or the solenoid?

 

Connect a vacuum pump to the mount and apply 230 mmHg of vacuum. The valve on the mount should move 80 degrees.

On the solenoid, check for continuity with a multimeter. Also, apply 12v power to it with test leads and see if it actuates.