Last year my '05 S60 had the hard brake pedal problem in the morning. Would go away in a minute or so. Based on what I read in the forums I replaced the switch behind the left headlight and the problem was solved. Well it just started again and a new switch does not fix it this time.
There does not appear to be any audible hissing indicating a vacuum leak from the booster on the firewall.
So what is the next step to solve this issue?

 

With the key off pump the brake pedal a few times to use up the stored vacuum.
Then turn the key on and make sure you hear the vacuum pump turn on and fill up.
If you do not then I would look at the vacuum pump.

 

Thanks tech. Is this the motor and pump I see on volvo parts connect for $850? Ouch! The pump does not activate after pumping the pedal. Any sensors or anything to check aside from the switch I already tried replacing before buying the new motor and pump?

Is this something I could try getting out of a junk yard? If so, would you happen to know what models/years I can cross reference with?

 

I would try adding power to the pump to see if it works. Also test for power to the switch to make sure you are getting power there. Also check the fuses under the hood there should be on there for the pump.

 

Yesterday morning I had my daughter pump the brake pedal then turn the key on. I thought I could hear the pump motor humming so I whacked it with a socket extension. It started doing it's buzzing thing and now seems to be working fine. Guess we'll see how long it goes.

 

Well atleast now you have an idea.

 

Thanks very much for your help.

 

Can you please post the part numbers or the part name, I am having the same issue.