2002 s40 swicth vacum brake solution

tanessex · Post by **tanessex** » 16 Dec 2014, 04:10

i bought for two time volvo s40, in 2011 first car was fine...but sold ,then 2014 nov just bought another s40 with in not good condition, i have same problem with brake (very hard push) when in the morning or left for more than 5 hour's.
the problem came in the swicth valve vacuum brake controler, which separately in the bottom of the swicth valve vacuum ,there is motor vacuum which was fine and work normaly (suck the air if you loosen the hose) when i jumper the connector which you can pull off from the switch valve vacuum.
here i like to share with other s40 owner or volvo expert, can i use power + (positive) from brake tail light to run the motor vacum ?
i already try it's work, cause there a relay in fuse box just need little volt amp run the relay to turn on motor vacum to get air supply pressure for booster work properly.
but i just don't know yet if i use in street, cause still now i must change the right roller front wheel
the question..... is it any side effect ?

and there more , both of my volvo if get run up to 100 km/h ... samething happen again (very hard push), but i don't know is it ABS working or another lack vacuum to booster, cause just happen only in volvo s40 which i already try lot of car ,ABS not work like this.
is there any volvo s40 user getting this problem or just my bad opinion

noted sorry for the word if i didnt wrote it properly

mf70 · Post by **mf70** » 18 Dec 2014, 13:04

Well, your English is a challenge, but it's a LOT better than my Bhasa!

I have a 2006 V50 (same engine). As I understand it, the Volvo has an electric vacuum boost pump. I hear it when I tap the brakes with the engine off. I'm guessing your pump isn't working. You say:

there is motor vacuum which was fine and work normally (suck the air if you loosen the hose) when i jumper the connector which you can pull off from the switch valve vacuum.

I am guessing that you are testing the electric vacuum pump and finding that it will pull a vacuum when given 12V. I would not just jumper a different power source. I would look into the wiring and see why/where the power is being interrupted.

For research, there are good wiring diagrams available and also copies of the VIDA maintenance program.

tanessex · Post by **tanessex** » 24 Dec 2014, 11:27

been try this method for 2 days, yes it work at morning or cool engines start, and can brake well..... but problem came up.... it sound when push pedal brake..... ha...ha....ha...........
next step finding same relay that will delay on for 5 minutes to cut the power of light brake after ignition on.... or simple way ... u can put swicth inside dash

Post by **FLXC90** » 24 Dec 2014, 15:34

On my XC90, I had a problem with the booster vacuum switch coming apart. If it fails, you will no longer have reliable brake booster vacuum. It is a device in the large vacuum line from the brake booster. The top plastic half will come off, dangling from its wires somewhere nearby. On my XC90, the device was between the airbox, and the engine, near the midline of the engine (front to back)I'll try to find a picture

With a broken switch, your pump will not run when it should

tanessex · Post by **tanessex** » 12 Jan 2015, 05:18

important to solve, first must know how the swicth vacum works, is it sensor works when lack of pressure or works when car after use.....

my volvo problem is the swicth sensor vacum , motor works fine.
after using positive from brakelight , everytime you push brake pedal, the motor will run.
but you will hear motor running everytime u brake, its realy annoying sometime.

last time before brake normaly work after 10 minutes running engine, only at begining brake hard to push, but after that brake normaly

so i need information how the swicth vacum work ? depend on pressure or when engine turning off

if depend on pressure... i cant not put timer delay on for 10 minutes.... because after 10 minutes the relay timer delay will cut positive brakelight and will no longer run the motor. its dangerous if the switch vacum works on pressure

but if the swicth work after engine turning off, this method can be usefull n cheaper

there are so many ways to put relay delay on depending which positive u choose, can be at spedometer light indicator... example indicator check engine or which is on when u put the key on

i still looking for relay time delay on around 10 minutes after on, lot of relay delay on when the power swicth off

its realy hard to explain in a word to explore

mf70 · Post by **mf70** » 13 Jan 2015, 13:26

Rather than trying to re-engineer the boost system, why not trace the actual fault? There's either a wire, a connector, or a relay that isn't operating.

VIDA has repair procedures #52 for mechanical checks and adjustments for the boost system.
VIDA has diagnostics for vacuum pump operation at "Symptom Related Diagnostic Procedures" # 275.

VIDA in the VMware image on this site is free, and will run on any PC.

JWA · Post by **JWA** » 19 Jan 2015, 15:09

Can you tell me how to check functioning of the switch and vacuum pump? I have a Volvo S40, 2001, I can pump my brakes up tight when the car is off but once I turn the motor on, I loose most of my pressure as if there was air in the lines. The car will still stop, but the most the pressure disappears. I do not hear the vacuum pump come on. I would go buy the pump and swap, but do not want to do so if it is only the switch, a fuse or something else.