Ok... Now my brakes have failed!!!! ABS light on, brakes don't work??? WTF?

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The Mad Hat Man said:
might account for ABS light if ABS sensor is clogged with crap?

maybe the ABS is now playing funny tricks, hence the pedal action?
If ABS/Traction control is having to work, then that could account for all sort of things....

oh - and it aint OBD2 compliant.

have yu checked brake fluid level?
Click to expand...

Yes, level normal.
 
Clarky130 said:
Wouldn't account for the sudden change in pedal action or ABS light though. And the braking action, whilst very poor, is still in a straight line.

The wife's car has a sat Nav and a Bluetooth OBD2 deely that can read fault codes - been trying to connect that up to my P38, but the OBD2 deely won't talk to the car for some reason...
Click to expand...
your the only one that can see/experience symptoms and unless glaringly obvious ,elimination of basic stuff first is best way of narrowing fault to exact cause
 
jamesmartin said:
your the only one that can see/experience symptoms and unless glaringly obvious ,elimination of basic stuff first is best way of narrowing fault to exact cause
Click to expand...

Agree James. First thing that went through my mind was 'popped piston seal' as that is what it felt like to me. I was expecting to see a half-empty reservoir when I checked... But it was full, and still is. No definite signs of fluid disappearing overboard anywhere yet either.

ABS light 1 hr before the symptoms appeared cannot be a coincidence. Reading the codes has to be the next step before I start pulling anything apart.

A kind forum member has offered to drop by tomorrow morning with a Nanocom, so we'll see what we get from that.
 
Datatek said:
I would bet on accumulator, if the diaphragm has failed all the gas will have escaped into the fluid.
Click to expand...

Any way I can check that without reading fault codes? What you describe seems to fit my symptoms, although the ABS pump runs and stops as normal on startup, suggesting it's successfully charging the accumulator.
 
Clarky130 said:
Any way I can check that without reading fault codes? What you describe seems to fit my symptoms, although the ABS pump runs and stops as normal on startup, suggesting it's successfully charging the accumulator.
Click to expand...

But it might just be filling the sphere instead of pressuring against the diaphragm, in which case it would pressure and stop but there would be an instant drop in pressure the moment the brake pedal was pushed as there would be no pressure reserve.:)
 
Datatek said:
But it might just be filling the sphere instead of pressuring against the diaphragm, in which case it would pressure and stop but there would be an instant drop in pressure the moment the brake pedal was pushed as there would be no pressure reserve.:)
Click to expand...

That figures. Reading the 'Depressurisation' procedure in RAVE, the pedal feels as though this has already been carried out. What I want to do is pull the accumulator off and check it, but RAVE simply says 'Remove Accumulator' - without actually telling you how! Does it just unscrew? Anyone ever done one? Carefully, I presume, as there's supposed to be 80 bar in there!!

Can they be had as a separate part, and are they expensive?
 
Depressurise according to RAVE and unscrew. About £80+VAT for a new one.
Might be a good idea to renew the fluid and bleed at the same time per the proceedure in RAVE.
 
Clarky130 said:
Found this writeup on RangeRovers.net - looks simple enough.

ABS Accumulator Replacement on a Range Rover 4.0/4.6/P38

More I think about this, the more it makes sense with my symptoms. Going to try and remove it now...
Click to expand...

That picture looks like contaminated, until that is rectified, I wouldn't in looking further yet. The picture on my phone also suggests the discs are shagged as they don't look special from what I can see
 
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Got the accumulator off. Pedal travel and pressure remains constant throughout depressurisation procedure - and didn't change earlier on either, ignition on or not (pump was running)

How can I tell if it's shagged?
 
Clarky130 said:
Got the accumulator off. Pedal travel and pressure remains constant throughout depressurisation procedure - and didn't change earlier on either, ignition on or not (pump was running)

How can I tell if it's shagged?
Click to expand...

Very carefully. And with nothing sharp. Probe the hole in the bottom of it, there should be a plastic seal that protects the bladder over the hole. If you can move it at all by pressure on the blunt probe or if you can insert the probe into the sphere, the bladder has collapsed and lost it's charge. Very, Very carefully mind. Probe pointing away from you or your face.
 
wammers said:
Very carefully. And with nothing sharp. Probe the hole in the bottom of it, there should be a plastic seal that protects the bladder over the hole. If you can move it at all by pressure on the blunt probe or if you can insert the probe into the sphere, the bladder has collapsed and lost it's charge. Very, Very carefully mind. Probe pointing away from you or your face.
Click to expand...

Done as suggeted. Probe goes into hole about 1.5 in and meets dead stop. No amount of pressure I was willing to put on it could shift it in any further.

Reattached accumulator to pump, and now, curiously, pump doesn't run when I switch the ign on....

Might just wait and see what Mr Nanocom says tomorrow...
 
If the accumulator has sprung a leak it has obviously done it when the brakes were being used. In that case the duff pedal is because Nitrogen has been introduced into the system when brakes were applied. If the accumulator had sprung a leak when the system was not pressurised, it would have bled back into the header tank as the fluid does and been evacuated through that. In that case you would have a hard pedal.
 
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Clarky130 said:
Done as suggeted. Probe goes into hole about 1.5 in and meets dead stop. No amount of pressure I was willing to put on it could shift it in any further.

Reattached accumulator to pump, and now, curiously, pump doesn't run when I switch the ign on....

Might just wait and see what Mr Nanocom says tomorrow...
Click to expand...


Maybe best to wait for Nanocom. Sounds a bit of an enigma.:)
 
Symptoms I have are exactly those as described in RAVE that occur when you depressurise the system - soft pedal, excessive travel.

I said earlier that reservoir fluid level was 'normal'... However, it's actually right to the top of the filler... Judging by where the min and max marks are, I'm guessing that's NOT normal... Could gas leaking into the system pipery cause that, by displacing fluid? I also noticed that, when the pump was running earlier to pressurise the system, it ran for around 20 secs or so... Maybe a tadge longer... And the fluid level in the reservoir dropped considerably, by about 2 inches, when the pump was running.

Seems like the accumulator still has SOME pressure in it... Either that or the plastic piston / bladder protector thingy has been displaced and jammed by a bladder leak?

Still doesn't explain why the pump now won't run, when it was before... Unless the ABS ECU has some kind of 'hard fault' mode whereby it just shuts the whole thing off after a while with a fault detected?
 
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