Brake Pressure warning from OBC.Help!!!!!!!!

[kentish]

Hi to everyone,

Just went for a little ride in my car and when I was two blocks away from home, got a warning from the OBC, Brake Pressure-See owners manual.

Brakes seems to be normal.

When I reach home, I depress brake pedal several time and the brake pressure message appeared again.


It seems to be linked to number of time I press brake pedal.


Anyone can help me


Kentish
540iA 1994 176000km

[winfred]

does your car have vacuum boosted brakes or hydrallic, if hydro there may be a failing sensor or part in the boosting system, if vacuum i have no idea, our us cars don't have any brake pressure sensors that i've seen

[kentish]

Its vacuum boosted brakes as in all 540i I think. I hope its a sensor failing .When depressing the brake pedal, I can hear pump kicking in to produce the air but after a few seconds I get the message -Brake Pressure from the OBC. May be there is a leak or sensor not working as the brakes are normal.


Kentish

[kentish]

Hi Winfred. I made a mistake, The Brakes are hydro brakes. No vacuum present. I can hear air being pump but just few seconds afterwards, I got the warning from OBC and then it disappear.

Kentish

[winfred]

this could be the begning of a problem, a bad connection or a dieing sensor, i've never worked on a v8 with hydro as our cars have vacuum, the parts should be much the same as the earlyer 6 cylinder cars, there should be a distrubution block with a pressure switch or two and somewear there should be a accumulator aka "bomb" it's about a 4" black metal ball this is what gives the brake pedel it's give, it could be failing, what happens when a bomb fails is it fills up with fluid and the nitrogen leaks out and the brakes get harder and harder as it fills up

[kentish]

I am thinking the same. Someone told me that if this Pressure accumulator goes wrong , the brake pedal will fill harder to depress. I suppose it could be that part. Fortunately its available at the dealer for around $200. I checked all other parts linked to brake system. Apart from some small leak, everthing is okie and no fault code is coming out of the diagnosis plug.


Thanks a lot for the help Winfred.

By the way, i thought that all V8 engine has hydro type brakes and there was not enough space in the engine compartment for the Vaccum servo to be installed. am i correct


Kentish

[winfred]

they stuck a dual servo vacuum unit right behind the left headlight with a linkage going to the firewall on the e32/34 v8s here

By the way, i thought that all V8 engine has hydro type brakes and there was not enough space in the engine compartment for the Vaccum servo to be installed. am i correct


Kentish