In reply to a message from kayla72 sent Sat 20 Jun 2015:
sorry bryan no as per haynes manual bleeding procedure–
kayla72
st helens, United Kingdom
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In reply to a message from kayla72 sent Sat 20 Jun 2015:
Stuart,
OK, if you are getting 30+ pumps on the brake pedal with the
ignition off after the pump has charged the accumulator
before the pedal ‘goes hard’ then you do not have a brake
pressure problem - i.e on that basis alone the accumulator
sphere is good.
However, if it takes the pump a whole minute to recharge the
accumulator before the pump stops and the red light
disappears then that doesn’t sound good.
To give you some idea of the relevant pressures:-
The nominal accumulator pressure when the red ‘BRAKE’ light
should extinguish is 1550 psi but the pump should continue
running until the pressure reaches a nominal 2700 psi. That
should happen with a considerable time lag between the red
light going off and the pump stopping - in my case some 7
seconds.
However, the ‘lower switching point’ when the pump restarts
is 2000 psi - i.e far above the pressure at which the red
light will reappear - but if it restarts after just one pump
of the brake pedal, that suggests that the top pressure in
the accumulator is way down on the expected 2700 psi but
that is certainly not the cause of your ABS light
illuminating because that (for reasons of low pressure)
should not happen until the accumulator pressure has dropped
to below 1400 psi.
It therefore follows that, with a permanent ABS warning
light, the problem is indeed in the ABS circuitry alone, not
the result of a pressure problem - i.e. a ‘static’ ABS fault.
I suggest you try doing the Teves ABS blink test again. If
it still only shows a code 21, try this.
Find an empty car park with a loose (gravel) surface. Drive
the car at 30 mph if you can and hit the brakes HARD to
cause the ABS to activate (if it will).
That may dislodge any debris in the ABS valve block.
BTW, did you open the bleed screws at each caliper when you
pushed the pistons back to fit the new pads? If not, you may
have forced dirty brake fluid back through the system to
contaminate the ABS valve block–
The original message included these comments:
33 pumps on the brake pedal and it starts hardening up
slightly.
–
Bryan N, now Jag-less, but fun while it lasted.
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Sat 20 Jun 2015:
hi bryan
when I say the pedal hardens I mean more along the lines of it
firms up slightly but does not go rock hard.
i have taken it out on gravel and there is no abs it just locks
up.
we have flushed all the old brake fluid out and filled with new
dot 4 fluid.
will pressure bleeding do any good and might there be an air
pocket somewhere.
and is it worth changing accumulater and pump.
again thank you for your time it is much appreciated–
kayla72
st helens, United Kingdom
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In reply to a message from kayla72 sent Sat 20 Jun 2015:
Stuart,
That’s very strange. When I used my hand to depress the
brake pedal (bearing in mind I’m an old 14 stone weakling!)
I could easily press it towards the floor with servo
assistance - i.e on a fully charged accumulator. When that
servo assistance was lost the pedal really did go ‘rock
hard’ and I could barely depress it a couple of inches.
I do wonder if your brakes are ‘spongy’ due to inadequate
bleeding and as I mentioned previously without good pressure
in the accumulator you will not be able to bleed the rear
brakes properly.
Without ‘hands on’ on the car it is difficult to be sure
what the problem is, particularly recognising the ‘hard
pedal’, but you may find this thread from the archives
interesting - particularly the last few posts which seemed
to cure a similar problem!
The original message included these comments:
when I say the pedal hardens I mean more along the lines of it
firms up slightly but does not go rock hard.
–
Bryan N, now Jag-less, but fun while it lasted.
Cambridgeshire, United Kingdom
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In reply to a message from Bryan N sent Sat 20 Jun 2015:
bryan
thank you greatly for your help.
it looks like it is pointing to accumulator so I think I will try
pressure bleed and look for another accumulator and hopefully get
her cured and back on the road.
many thanks stuart and hopefully I can update more as I go–
The original message included these comments:
assistance - i.e on a fully charged accumulator. When that
–
kayla72
st helens, United Kingdom
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