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Discussion Starter #1
Hi all. My brakes failed right before July 4. I searched in a panic and ordered the accumulator. That wasn't it.
ABS/TC/brake lights all on. No power assist with only back brakes functional. The hydro-pump turns on for about 30 sec at ignition(a bit weak). The power assist has been returning after the rangie has been sitting for a while, or after my efforts to bleed the system possibly. It then runs for a while. I think heat may have something to do with it because it returns for the longest when its starting from cold. From what Ive read in my searches, I think that the problem is in the master cylinder. I read that there could be a plasic thingy in there but my rangie is a bosch 99'. Can anyone tell me if i'm on the right track? Cheap fix?
Hydraulic pump functional.
 

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1995-2002 Range Rover P38A
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193 Posts
It is probably the ABS booster... Brand new they are an a$$ load of dough... Search for a used one. Just to make sure do (or have a shop if you cannot) a vaccum test on the booster.
 

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1995-2002 Range Rover P38A
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1,851 Posts
Hi

The brake system of the P38 RR works with positive high hydraulic pressure of the brake fluid.
The fluid is guided towards the brake calipers through the proportional regulating valve operated by the brake pedal in combination with solenoids that cut off or apply the brake fluid flow towards the calipers when this is required by the ABS or traction control systems. There is no vacuum assist.

If the system fails to operate the brakes properly there is most likely not enough hydraulic pressure. This could be caused by the pump that is weak, a non return valve that is faulty in the pump or a leak in a part of the booster system. From your description the pump is suspected. Try to change the black ABS power relay in the fuse box. The ABS pump should run until it is stopped by the pressure switch after reaching 180 bar of pressure in the system.

Regards

Jos
 

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Discussion Starter #4
Hi. Thanks for responding. If I let the truck sit and cool off, depressurize the system with the brake pedal method, unplug the air compressor, and listen for the pump, I can hear it on for about 30 secs. I then have power brakes on all 4 wheels and everything works fine for a while. Then the ABS light comes on. I'll have power brakes for a little while longer until I get an ABS fault. Then ABS/TC/BRAKE all come on and I lose power assist as well as front brakes.

What can cause power assist failure as well as front brake failure but still let the rear brake work? When I stomp on the brake the rear suspension rises a lot.

I'm more concerned with getting the front brakes working at the moment. Then i'll worry about the power assist.

What a headache!
 
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