Hi, I was changing the air filter in my 2004 XC70 and this part pretty much fell apart when I touched it. What is it ? It seems to be in vacuum or PCV system, but I can't find it on any diagrams. Any chance taping it shut would fix it? Thanks in advance.

 

Brake vacuum pump switch. Usually when they break the vacuum pump runs all the time, overheats and seizes up. Won't do you any good to replace the switch if the pump is seized! (make sure your vacuum pump still works BEFORE replacing the broken switch) There are a few variations so make sure the one you order fits your car. And there are aftermarket switches available for about half the price.

 

Thanks, never would have guessed. I put a vacuum gauge on the tube that goes down to the pump, started the car and pumped the brakes. The gauge did not move, so I'm guessing the pump is bad, unless there is a different procedure to test the pump. Not sure if the switch failed in on or off position, I don't think it failed during operation, the top just broke off when accessing the air cleaner, a lot of the plastic fittings on the car are brittle. I got 12 V across the two green wires that come out of top of switch, do they power the pump, or activate the switch?

The brakes seem normal to me, could it be I've been without this system for a while, how important is this vacuum assist system anyway, would I be unsafe to leave it as it is?

 

When you first start the car (with VVT on both cams) there is very little manifold vacuum created, and the pump makes up for that. When the pump is not working customers complain that it's harder to stop the car when first moving. (start car, back out of parking spot, hit brakes and they are harder than normal)

 

I guess without the vacuum pump I just have to apply more pressure on brake pedal. It does not seem too bad to me, but maybe I should fix it for my wife, since she drives this one.

Any idea if the vacuum test I did confirms pump is not working? I'm still not comprehending how the system functions, does the low vacuum on start up actuate the switch that powers on the pump?

 

If you jump the 2 wires in the switch connector plug (paperclip) - that will run the pump (if the fuse is good)