Hi group! The abs pump on my 99 Rover HSE is running very frequently. It runs for a few seconds every few minutes with the vehicle parked (ignition on). And, it runs for a few seconds after every brake application. rangerovers.net goes over some diagnostic steps, but it doesn't go in depth on my problem other than saying that there is a leak and the check valve may be bad. With a system that runs at a high pressure, I'd suspect that I would be able to hear an air leak? I can hear a little hiss from the brake pedal when I initally step on it, but sitting still the entire vechile is very quiet, yet the pump will run every few minutes. Any ideas? I'd hate the spend the $$ on the abs pump and find out that's not the problem.

Thanks for any advice,
Dave

 

If I remember right they have an accumulator on that system and if so, it is failing and not keeping up your brake pressure.

 

Thanks for chiming in! There is an accumulator next to the abs pump and from what I have read it seems to be a part that commonly fails. However, the diagnostic procedure on rangerovers.net indicates that if the pump runs on it's own without actuating the brakes, than the problem should be a leak and not the accumulator. I would like to hear otherwise as the accumulator is cheaper and easier to replace!

 

What happens when you leave it for a few hours and start it back up, how long does the pump run for? It sounds like yours is operating properly, I hear mine come on just about every time I use the brakes and hear it while stopped at a light every few minutes. My accumulator is dying because it comes on for about 43 seconds when I start the vehicle after having let it sit for a few hours. I don't think there is anything wrong with yours but, if you feel inclined to replace something, it is probably the accumulator. Also, when checking for leaks, you are checking for brake fluid leaks and chances are won't hear them like you would with an air leak.

 

Just had the ABS pump replaced on our old P38. Entire pump + accumulator / pressure switch. From what describe, either the switch itself or the accumulator is your likely culprit. You might try bleeding it and see if that helps, but I would start with an accumulator after that as was stated above and next move to the switch. I had almost identical symptoms and didn't deal with the problem until the pump burnt out - that becomes an expensive issue.

Mike

 

Good info! The pressure switch does sound a little suspicious. Usually the pump runs around 3-5 seconds every couple minutes, but a few times I've heard it blip on for a only fraction of a second. When I start the car in the morning, it probably runs for about 30-45 seconds.

 

Then you most likely have a bad accumulator, so you might want to start there since it is not as expensive as the pump, and usually have to replace it with the pump anyways. The pressure switch is about 40 dollars if you want to replace that too but, I would replace the accumulator as it fails on a regular basis.

 

I went ahead and replaced the accumulator. Pretty easy to replace, but it didn't help too much. Now it seems like the abs pump will run after every 3-4 brake applications where before it seemed to run after every application. A little better. But, it will still run on it's own every few minutes with the vehicle parked and the ignition on. There are no brake fluid leaks. I can try the pressure switch next. Is this available on its own and does anyone have tips on replacing it? According to the manual I have, it says that the pressure switch is replaced along with the pump.

Other than the switch, could the system just need bleeding? I suppose I should go through the procedure before I try the pressure switch?

 

How long does the pump run when you first start the rover after having let it sit for a few hours?

 

I timed it today - 30 seconds.