Clarky130 · Mar 17, 2012

As per thread title... Never rains but it pours!

Symptoms - ABS light on constantly. Initially there were no other symptoms for about 10-15 miles, then sudden brake failure - as in, hardly any braking effort available at all. Pedal goes almost all the way to the floor. Pumping the pedal will give me just enough braking effort to bring it to a stop. Fault is constant, ie doesn't change at all with switch off / switch on.

Any thoughts where I should start? Would a leak in one brake circuit bring on an ABS light long before any symptoms of a fluid leak are felt through the pedal?

Pedal doesn't feel any different, engine on or engine off. Soft, goes a long way towards the floor.

I suspected a leak, failed caliper piston seal, busted line, etc... But the reservoir is full!

jamesmartin · Mar 17, 2012

get someone to pump pedal and see if fluid splashes back in reservoir

rodntod · Mar 17, 2012

Sounds like the pump or accumulator have failed.

jamesmartin · Mar 17, 2012

does pump run and then switch off when ignition switched on ?

Clarky130 · Mar 17, 2012

Yes. Pump runs for about 15 secs, reservoir level drops, pump shuts off.

Power off, pump pedal, fluid level slowly rises in reservoir. No difference in pedal effort, power on or off.

fanatic · Mar 17, 2012

Brake modulator know issue after checking basics repair kit available. Accumulator common fault

fanatic · Mar 17, 2012

If it is modulator, do not buy a second hand one as it will be as bad as yours,the repair is special steel washers and not the plastic ones. I rebuilt mine

Clarky130 · Mar 17, 2012

There is possible evidence of a 'seepage' leak on the inside of the OSR brake dust shield - cannot yet see where it is coming from. Will remove wheel and check. Not sure why that would bring on the ABS light though. Also, I don't appear to have lost any fluid from the reservoir.

Clarky130 · Mar 17, 2012

Bugger... Guess my off-roading weekend just went out the window then...

fanatic · Mar 17, 2012

Out and about, search my user name advance search clicking pedal

Clarky130 · Mar 17, 2012

Not convinced that caliper is leaking. If it were, I would expect it to be plastered in fresh fluid and for it to be everywhere. As it stands, the 'seepage' only appears below the axis of the half-shaft, seems more 'oil-like' in nature, and seems to have been going on for some time. I think it's more likely a half-shaft end seal leaking, and therefore a red herring for my brake problem... Anyone vehemently disagree?

jamesmartin · Mar 17, 2012

its not a hard job to remove piston housing from slides to check for leaks/dampness its not allways fluid loss but air sucked in on release of pedal,clamping hoses can help narrow fault down

fanatic · Mar 17, 2012

Looks like no pad on inside, I'm on a phone at moment

Clarky130 · Mar 17, 2012

I've read up on the modulator issue... I remain to be convinced that that is thenproblem, however. Although the failure occurred suddenly, I still had some braking effort... Just not much. My pedal has never clicked, banged, jumped, or felt odd in any way. It does, for all the world, feel like there is alot of air in the system... But if so, how did it get there 'suddenly'... And why did I have an ABS light on for at least an hour before this happened, with no untoward symptoms whatsoever? It's very puzzling.

I've had all 4 wheels off the ground individually, and there is braking action at all 4.

I need a way to read my fault codes.... I have a generic OBDII interface based on an ELM327 chipset, but can't find any compatible software to run it... Anyone know of any I can download?

jamesmartin · Mar 17, 2012

fanatic said:
Looks like no pad on inside, I'm on a phone at moment

yes looking at picture it does look odd lot of debris there

jamesmartin · Mar 17, 2012

check brake pads etc first

The Mad Hat Man · Mar 17, 2012

Just a thought - my first impression, looking at those pics is that an oil seal has gone. That would account for all the debris attached to the pad, as the oil would collect the dust, it would also account for the oil stain and the lack of braking.

jamesmartin · Mar 17, 2012

not a bad call mr hatman

Clarky130 · Mar 17, 2012

The Mad Hat Man said:
Just a thought - my first impression, looking at those pics is that an oil seal has gone. That would account for all the debris attached to the pad, as the oil would collect the dust, it would also account for the oil stain and the lack of braking.

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...

The Mad Hat Man · Mar 17, 2012

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?

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