No brakes when first used (parking lot speeds) '04 V70 R

Post by **matthew1** » 25 Feb 2011, 13:55

Quizzed the wife yesterday more about the brakes... she recalls the pedal takeup being high. Meaning: the pedal did the opposite of going to the floor.

Post by **jimmy57** » 25 Feb 2011, 14:10

what a vacuum boosted power brake pedal feels like with low vacuum.

Post by **matthew1** » 25 Feb 2011, 14:34

Awesome, thanks again Jimmy. So it's low vacuum.

Post by **jimmy57** » 25 Feb 2011, 16:09

When you are home and can see for yourself you will likely have the for sure answer.
My suspicions are based on having seen a number of those pump systems not working until the vacuum switch is tapped with a screwdriver or other light object. I have seen some with faulty relays too. Also several with switches that stick on and pump runs for long periods and burns up (wears out) the pump. The key on, engine off brake pedal pump test is the easy first step in diagnosis. IF you tset drive it the period in which the problem of no electric pump function causing really noticeable issues is brief and temp dependent. It is a cold start problem almost always.

Post by **dan777** » 25 Sep 2011, 14:10

I wonder how was the problem solved...
I have exactly the same symptoms, 2006 V70 2.5T, after a cold start I have no brakes for a minute or two, pedal feels hard. I know there are a few other parts around the vacuum pump that can cause this problem: fuse, relay, vacuum switch, check valve. Anybody knows how to check the switch or the valve, I want to make sure before I start spending money on the pump. Where is the relay located?
Thanks in advance.