2002 s60 No fluid flow from ABS to Caliper

vmaxmike · Post by **vmaxmike** » 14 Dec 2014, 09:07

Hi,
Got a brake problem on my project S60 non turbo was hoping someone might have experience on.
I was bleeding brakes and discovered Left front and Right rear calipers are not receiving hydraulic pressure (no fluid) and therefore are not braking. Open bleeders and pedal remains firm. I loosened and checked the two out lines from the ABS unit going to these two calipers and no fluid came out!. The other two brake lines going to the other two calipers bleed normally and work fine. So my ABS unit appears faulty on two of the four lines. Is the only solution a replacement ABS or is there way to free up the internal components somehow? Is something seized up internally?
If I have to replace the unit, would I have to buy a Volvo software download to make it compatible with my car? Thanks!

Post by **regent** » 15 Dec 2014, 11:34

It is not usual for the ABS unit to fail mechanically like that; was the fluid clean of contaminants? Also, can you hear the ABS on key up; any brake system fault messages on DIM?

I would compress the front calipers' pistons (with all lines connected) to see if fluid can get back to the MC Reservoir, and hope that solves it.

If it does, you still have to verify your brakes are 110% reliable before take off!

Can you give this a try and post back,
Thanks

vmaxmike · Post by **vmaxmike** » 15 Dec 2014, 14:59

I'll try your suggestion hopefully tonight if time permits. No, fluid looked pretty old from previous negligent owner so I removed and completely emptied reservoir getting residual off sides by lots of shaking and refilling with clean dot 4. Not sure what ABS noise to listen for on key up but now that you mention it I'll put an ear to it with an assistant turning on key. NO ABS light or brake fault messages are appearing with car running. Thought maybe putting direct voltage to the pump motor itself might free up the frozen ports but not sure that's a wise thing to do??

vmaxmike · Post by **vmaxmike** » 16 Dec 2014, 14:07

Ok, I compressed LF caliper which is the one with an issue but it seemed to be full of nothing but air as there was no change in fluid reservoir. I then disconnected the out line from ABS to that caliper, pressed hard on brake and nothing comes out. What are your thoughts please on putting voltage to pump as mentioned before? If I need to replace the unit, does it require software do you know?

Post by **regent** » 19 Dec 2014, 11:00

Sorry for the long reply -

I have never had to experiment on an ABS pump like that...
AFIK, the replacement ABS module only requires to be initiated so it can talk to the other intelligent units.
(I suggest a junk yard visit)

But before you condemn it - if you have VIDA/DiCE, you can 'talk' to the ABS and look for pending proprietary codes that do not necessarily trigger a message or a MIL but may tell you some more. Let me look at my VIDA; I believe there are certain tests that can be run on the ABS unit.

If you do have a faulty ABS module (other than the pump and valve assy), the electronics can be fixed, it is not that hard.

Post by **regent** » 20 Dec 2014, 10:51

Follow up: Yes, there is a test set on the Brake CTRL Module that lets you test run the ABS pump and command each of the I/O valves in the ABS module to open/close. I would do that before condemning the unit.
I have attached the test description from VIDA. Hope this helps.

Post by **FLXC90** » 23 Dec 2014, 14:16

No insult intended here, but it isn't mentioned in the thread: do you have a brake bleeder like a mityvac or something? or are you doing it all the old-fashioned way?
If you can draw fluid UP through the line from the caliper, then you can retract the caliper and try to force fluid into the ABS to unseat a jammed valve, if that's what it is. Obvious caveats for protecting the ABS, but you can't do it with air in the line.
If you remove the electronic module, can you finagle the plungers on the control unit? That may reveal jammed/stuck parts also-just a thought.

SweedSpeed · Post by **SweedSpeed** » 23 Dec 2014, 17:41

Sorry you're experiencing this issue. I had to replace all four calipers recently and a month later am getting 'brake failure service urgent,'. So no advice but filling your thread for knowledge. Good luck!

SweedSpeed · Post by **SweedSpeed** » 23 Dec 2014, 17:42

*following

vmaxmike · Post by **vmaxmike** » 26 Dec 2014, 06:52

Hi Regent,
Thanks for the attachment pdf test description but I'm not sure where to go with that since its only general info and does not indicate "How" to activate a given i/o valve to open or close, only that you'll hear a click sound when doing so. I'm not familiar with VIDA/Dice other than its Volvo proprietary software for servicing the cars. I would like to do this test but need to know which pins to apply voltage to perform test on the given pump valve for specific wheel. Assume then its a special electronic tool that does this?