[Ahmedwanas]

Hello guys, I need your help with a issue with my abs brake pump. My abs pump runs constantly with no stop whenever i turn the ignition on. I changed the accumulator, pressure switch and abs relay in fuse box and the problem still exists. If the ignition is switched off there is no problem whenever i turn the ignition on the pump never stops. Its a mark II p38

 

[Bolt]

Well, as you have eliminated all of the parts that support the Abs pump, you are left with a worn out pump itself.
How are the brakes?
What year is this? How many miles on it, and where are you in the world?....Could be helpful to know.....

 

[Ahmedwanas]

Well, as you have eliminated all of the parts that support the Abs pump, you are left with a worn out pump itself.
How are the brakes?
What year is this? How many miles on it, and where are you in the world?....Could be helpful to know.....

The brakes are working when the pump is running, but i removed the abs relay to avoid burnt pump so now i dont have hydrulic pressure when i press the brakes i have to press the brakes really hard to stop the car.
Its a 1999 330,000 km
Am in Egypt

 

[Richard_G]

You say it never stops but how long have you left it for? With a decent accumulator the pump will run for around 40 seconds to build up pressure. If it runs for over a minute I'd start to assume a problem, but less than that is normal.

 

[Ahmedwanas]

You say it never stops but how long have you left it for? With a decent accumulator the pump will run for around 40 seconds to build up pressure. If it runs for over a minute I'd start to assume a problem, but less than that is normal.

I left it for more than 3 minutes, i excpect there is a problem thats why am asking if anyone hd a similar issue

 

[Escape]

The pump can only run if power is supplied, so the problem must be relay, pressure switch or wiring. Unless the pump is unable to build pressure and the system is actually functioning correctly, desperately trying to get to operating pressure.
The relay is activated with ignition live (which is why the pump stops with ignition off, this also proves it isn't a sticking relay) and grounded through the pressure switch. There's a chance the wire is damaged and grounding somewhere. Easy to check: unplug the pressure switch and measure for continuity between pin85 of the relay and ground. Should be open loop.

Filip

 

[Bolt]

I am leaning towards the "Pump is trying, but not quite getting to the required pressure to switch off" theory. They do wear out, and this would be a symptom.
We have not put in Dot 5 brake fluid have we?