My 2004 XC90 died while driving down the highway yesterday. The vacuum pump in the front of the engine had been running constantly and when the car died yesterday there is a part up the line from the pump that sort of blew up. The part is directly to the left of the fuse box and has multiple houses running off it. Upright and cylinder shaped. It had a spring inside of it. Does anyone know what this part is?

 

Brake vacuum pump switch. Chances are that with it continuously running it burns up the pump so I recommended replacing both parts.

 

Why is a vacuum pump needed on a throttled spark ignition engine? Wouldn't the intake manifold vacuum be sufficient to supply the needed vacuum? Does turbocharging render the intake manifold incapable of producing enough vacuum to operate vacuum assisted brakes, etc. ?

 

Thanks for the advice. Would it be that even if we weren't having brake problems? Also, would that make the car not start now? I appreciate the advice.

 

It helps with braking when you don't have enough vacuum like when the vehicle is off or just after start up. It wouldn't cause it not to start