FLXC90...I can "feel" the clicking when I touch the pump. Did you have this symptom on yours?

On my 2004 XC90 T6. The brake vacuum pump, UP28, was clicking upon cold start this morning. it was cold. Negative 5 farenheit. The pump would rapidly click for a second, repeating every ten seconds. the noise went away when the engine warmed up Is this a pump going bad or something else, like the sw...