Nissan Repair: Ticking rattle AFTER engine is off, exhaust catalyst, nissan pathfinder

Question
Vehicle is a 2002 Nissan Pathfinder with a 3.5L V6. VQ35DE motor with 4 speed auto. There is a rapid ticking rattle coming from the passenger side firewall in the engine bay AFTER the engine has been turned off. Sounds like a solenoid. Rattle lasts 10-15 secs and stops abruptly.

What is this?

Answer
You may be hearing the exhaust catalyst cooling down. I looked in the service manual, and don't see any solenoids in the area you are describing. Are you sure its from that side of the car? If a solenoid is clicking you should be able to feel it clicking with your finger. Just make sure that you don't burn yourself.