2004 XC70 Hard Brake Pedal, 31400693 Topic is solved

Post by **cuhfs** » 21 Feb 2021, 16:04

2004 XC70 has a very hard brake pedal after replacing a broken Brake booster vacuum switch. Any idea where the brake booster vacuum pump fuse may be? Need fuse number and location, preferring to check for blown fuse before replacing the booster pump.

Post by **- Pete -** » 21 Feb 2021, 21:45

Here are a couple other quick things to look at that can cause the hard brake pedal.

Verify that the top cap on your new switch is actually “on” and sealing well. Also, verify that your brake booster vacuum ejector hasn’t separated. The plastic becomes brittle & the endcaps/nipples can and do detach.

Brake booster vacuum ejector link

Edit: good catch Steve, thanks!

Post by **abscate** » 22 Feb 2021, 03:05

Different ones for p80 and p2chassis

8677893 For P80

30744402 For P2 2005-

2001-2004 ?

Post by **oragex** » 22 Feb 2021, 05:42

The switch stays with the connector towards the front of the car, the hose where 'Motor' is stamped goes to the vacuum pump, also push the connector all the way it. You can test the pump: in the morning before starting the engine, turn ignition to POS II and press a few times on the brakes, the pump should whirls to prime the vacuum

Post by **abscate** » 22 Feb 2021, 08:45

I want to say that this stuff came about with VVT and the elimination of SAS pump and valve.

ON cold start, the P2 engines pump cold air in by pushing VVT, which eliminates engine vacuum for the first minute or so. The pump gives you brake boost during this time.

Post by **cuhfs** » 27 Feb 2021, 12:36

Thanks to oragex's (above) video posting I realized when I put the new Brake booster vacuum switch in I had the plug in back which is backwards. flipped it around to plug in front... and problem solved. Installer error.

goldxc70 · Post by **goldxc70** » 19 Apr 2021, 18:22

My '04 XC70 Brake booster vacuum switch also flew apart recently. Luckily, all the bits stayed in place and I put it back together using zip ties for the moment. I guess the lifetime for these switches is about 17 years. Also I assume it's a dealer only part?

Post by **abscate** » 21 Apr 2021, 02:46

goldxc70 wrote: ↑19 Apr 2021, 18:22 My '04 XC70 Brake booster vacuum switch also flew apart recently. Luckily, all the bits stayed in place and I put it back together using zip ties for the moment. I guess the lifetime for these switches is about 17 years. Also I assume it's a dealer only part?

Volvo only butFCP has them for about $75

Junkyard or eBay, too.

Part number 31400693