Hello and Welcome to Justanswer, My name is XXXXX XXXXX X am here to try and assist your with your question
sounds like the hcu may be bad
Is that the hydraulic control unit? Where is it located?
here is a pics and yes the hydralic control unit has a valle that sticks and causes a low pedal the only way to fix is to replace it
here is the location
Is this a dealer only part and do you know if a less expensive re-manufactured unit is available?
this is a dealer only and I do not know of any places that rebuild them may be able to find it cheaper on the internet
I forgot to add that the ABS indicator light is not on when the engine is running, so would it still indicate that this is the problem?
if the pedal is sinking like a bad master amd the master has been replaced then the return valve is sticking in the hcu and allowing fluid to bleed back to the master. This problem will not turn the light on
crap gets stuck in the valve and causes it to stick see this all the time
I would imagine your beak fluid is black or was
There is a proportioning valve off the side of the master cylinder...could this be the problem instead?
no have never seen that cause a soft pedal
Yes, the brake fluid was black when I first started bleeding the system. With the number of times the system has been bled, new fluid comes through at every wheel.
then it has been flushed and the fix is the hcu
A couple of forums mentioned that improper adjustment of the parking brake could cause this....I haven't checked that yet. Could this be part of the problem?
you have disk brakes in the rear and the parking brake is separate from the regular brakes so no
there are completely separate from each other
Sounds like it must be the hcu then. Have you ever seen this problem with a defective caliper....would you suggest that I replace the rear calipers first?
if it was it would be leaking and if there are no leaks then no
There were no noticeable leaks.
then it needs a hcu like you said
Thanks for your help. I'll try replacing the hcu.
thanks for the accept
If equipped with the 4 wheel anti-lock brake system and the Hydraulic Control Unit (HCU) has been replaced or is suspected of containing trapped air, bleed the brake system using the procedure below. Conventional brake system bleeding cannot remove the air trapped in the lower portion of the HCU.
If a spongy brake pedal is present and air in the hydraulic control unit is suspected, use the following procedure: