TAKdriver · Aug 15, 2010

Schmarnst said:
The light goes out as soon as the engine fires. It illuminates as the key is turned to the auxiliary position, but as soon as you turn it past that point it extinguishes. I've got now to the point now where the pedal is rock hard, the front brakes bleed normally but when I open the bleed nipples on the rear, there is no loss of pressure... I've traced the brake lines back and opened them up at intervals, but still no fluid, until eventually I traced it back to the master cylinder where I completely removed the rear brake lines, still no loss of pressure and no brake fluid! What the heck do I do now?
Do I need a new master cylinder? Or does this all boil down to that blasted ABS pump? And if so, does anyone have a working one that I could buy?

It is likely just to be the pressure switch. See my thread under FAQ's on testing your abs pump.

Derek Ward · Aug 15, 2010

If you have no rear brake pressure, it can be one of 4 things:

Hydraulic Booster Unit
ETC Valve Block (If fitted)
PCRV (Pressure Conscious Reducing Valve)
ABS ECU

Pressure to the rear wheels is controlled first by the PCRV, then by the ETC if fitted and then by solenoid valves in the hydraulic booster. If the PCRV isn't passing or the solenoid valves aren't opening, you won't get any pressure. I would think it unusual that both solenoids to the rear wheels would go. I would suspect the ABS ECU I think. Maybe worthwhile picking one up from Fleabay. I don't think they go for a lot of dosh. Much cheaper than a hydraulic booster unit anyway.

TAKdriver

Active Member

Derek Ward

Active Member

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