Caravan 3.3L brake booster pump keeps coming on ...

[Cobra_Sam]

Hallo all,
Has anyone come accross this issue ....
1992 Dodge Caravan 3.3L the brake (booster) pump comes on and buzzez for 20 seconds, switches off for about 30 seconds then comes on again. It keeps on doing it all the time over and over.

[theFREAKnasty82]

I don't think that's the booster you're describing, sounds like your ABS pump is acting up, I'd try locating the pump and disconnecting it and see what happens.

[Cobra_Sam]

Originally Posted by theFREAKnasty82

I don't think that's the booster you're describing, sounds like your ABS pump is acting up, I'd try locating the pump and disconnecting it and see what happens.

That's what some people call it but in fact it pressurises the brake fluid and does what the big old vacuum booster used to do. If you look at the master cyclinder on cars today there is no vacuum booster. Anyway.... the pump keeps coming on and going off and I would like to know if it's the pump I need replacing or the brake master cylinder unit with the perssure resavoir on it.
Thanks
Sam

[theFREAKnasty82]

does your brake pedal pulsate when you try to stop?

[theFREAKnasty82]

If I'm not mistaken, all the booster does is apply engine manifold vacuum and atmospheric pressure to make the brake pedal not as hard to apply. Ususally, if a booster goes bad, you'll notice the pedal going rock hard (if I'm understanding you correctly by what you meant in your last post) or a drastic fluctuation in the engine RPM when you hit the brakes. The booster doesn't pressurize the brake fluid, the ABS pump, yes that will increase brake fluid pressure.