Searched forum but could not find info on what I think is an electric vacuum pump that aguments the brakes power booster. Noticed this weekend while doing routine maintenance that when you turn key to on, the unit whines real loud and gets hot to the touch in about 30 seconds. It never use to make this sound.

There is a hose thast goes to a sensor w/ a, I think brown, two wire connector. Other main hose goes to brake booster.

I read somewhere else that the sensor is bad and is causing motor to run all the time. Is this the case and that I never noticed the sound the motor makes b/c engine is running? Or is the the electric vacuum pump gone or going bad? Where is a good source for parts?

Thanks!

 

Does any one know the conditons under which turn this electric vacuum pumps is suppposed to be on and then off? Is there a certain vacumm level that should be present at vacuum switch when the vacuum motor is on or off?

Still trying to dermine if this vacuum motor running and getting hot is normal or if it is problem now or a future problem. I called Volvo dealer to inquire. They had know clue to what I was referring to. Initially, could not even find electric vacuum pump in computer. Never did find vacuum switch in computer. Told me to pull it out and bring it in??

 

The pump only turns on when the booster is low on vacuum. If it runs all the time the valve is most likely bad.

 

Hi Blueforester, I have a similar case with my S60 2.4 170 2004. When I turn the ignition key into position 2, the vacuum pump immediately starts buzzing/whining. Normally it only does that when I pump the brake once. When the engine has started, it keeps running. My friend kind of burned his finger trying to locate the buzzing sound. So it's hot. Funny thing is, it doesn't always do this. Now the weather is really damp today and this might affect it? Is there a sensor that I can clean? I was wondering if you have found the solution?

 

take the hose that connects to the diaphragm (the little black thing with 3 lines running to it) and then cover the hose with your finger, if it turns off your pump is ok. Those black vacuum diaphragms go bad all the time.

 

thanks for the advice RVA-Tech. I've done the test and found out that there's a vacuum, but the pump did not stop. Now my attention is aimed at the brake booster switch. After taking it apart I heard a vacuum his, so no vacuum leak in the diaphragm. I did a resistance test on the switch after taking it apart with my multimeter and it turned out that it is not breaking the circuit. I'll get a spare one and see if that works.

 

I have a 2002 volvo s80 t6 I replaced the booster vacuum switch but now my brake pedal is hard I was wondering if I installed it wrong?