Brake help. (2 Viewers)

[jmcboots]

Good afternoon Gurus!

I need help. '00 LX470 265K on her.

So about a week or so ago, I lost almost all braking power. After a bunch of reading here, I ordered up a master cylinder kit and made plans to rebuild it. While I had the MC out of the car, I took the ABS pump motor off and had a look at it. It was a mess. Some of the metal was worn down to the plastic on the motor armature. I will post a picture shortly. Anyway I cleaned the motor up put it all back together and drop 12volts on it and spun nice and strong.

MC kit comes and I replace the plunger and put all of that back together and throw it in the car and start bleeding. Fronts bleed fine, When I go to do the rears, I get almost nothing. I go and check the motor accumulator, and I am pretty sure it is not running. After some more reading around here about bleeding the accumulator I loosen all four brake lines at the MC and the fronts pump great and I tighten them up, but I can not get anything from the rear lines at all.

Is there a way to test the motor / accumulator in the car? Is there something in the ABS computer on the MC that would shut it down? I read something about that somewhere but I can not find that thread now.

Why would the master have front pressure but no rear pressure?

Oh and I should add, the VSC computer is dead, so I cant read codes from it. Its been that way for about a year. I finally ordered some of the 4k resonators to do that repair as well.

Thanks in advance!

 

[jmcboots]

Before:

After:

 

[JunkCrzr89]

The rears are notoriously difficult to bleed without Techstream. Otherwise, just crack them open and let gravity work it’s magic on the rears overnight.

 

[jmcboots]

The problem is I am not getting anything for the read wheel at the Master Cylinder! not at the wheel cylinders.

 

[jerryb]

are you sure you're correct Mr. Junk?

 

[suprarx7nut]

I believe there's a brake pedal sequence that runs the ABS motor indefinitely. 40 pumps perhaps? You can do it via techstream as well, but there's a pedal sequence too. I recall doing it on my 99.

I think you need to track down that sequence via one of the online manuals or someone here. I can grab a screenshot of the FSM later today if you'd like. Just might have to remind me.

 

[Malleus]

^^^this, or Techstream.

Are you certain that the master cylinder was completely bench bled?

 

[AlpineAccess]

I'm not sure how you're bleeding them; this is how I did mine:

Pumped pedal 40 times or until pedal is soft. Removed master. Rebuilt. Reinstalled. Filled with fluid. Keyed ignition to fill booster. Turned vehicle off.

Bled fronts with the press pedal and hold-loosen-bleed-tighten-release pedal method until fluid was at them.

Turned key on and had helper press and hold brake pedal. Opened rear bleeder, brake booster kicked on and pushed fluid. Would close screw and check for fill every few table spoons and top up. When done I went back to fronts and re-bled with vehicle off. This step didn't seem necessary as no air came out.

Did 40 pumps until pedal soft, leveled brake reservoir. Did not have any lights, but went to nearby gravel road and activated ABS with a panic stop/slide. Went home, had helper press and hold while I bled all four corners again. Did 40 pumps until pedal soft and set level on brake reservoir. End of job.

It sounds like either you have air in the master (do 40 pumps or until soft without key in ignition, and then key on to cycle booster pump) or just as easily you could have clogged bleeder screws.

 

[AlpineAccess]

The rears are notoriously difficult to bleed without Techstream. Otherwise, just crack them open and let gravity work it’s magic on the rears overnight.

I've never had any issue bleeding the rears, I think they are way easier than the fronts IMO.

Just key ignition on so pump is cycled/pressurized. Put a stick on the brake pedal to apply pressure (or have helper press them) and then crack rear bleeder screw. The pump detects drop in pressure and pushes fluid through. The hardest part about doing the rears is remembering to go back up front and add fluid to reservoir.

Side note, both of my rear bleeder screws had lost their caps and were seized closed so it seemed like I had a problem bleeding them. I just got new bleeder screws with dust caps for $3 and it's all good.

 

[JunkCrzr89]

I've never had any issue bleeding the rears, I think they are way easier than the fronts IMO.

Just key ignition on so pump is cycled/pressurized. Put a stick on the brake pedal to apply pressure (or have helper press them) and then crack rear bleeder screw. The pump detects drop in pressure and pushes fluid through. The hardest part about doing the rears is remembering to go back up front and add fluid to reservoir.

Side note, both of my rear bleeder screws had lost their caps and were seized closed so it seemed like I had a problem bleeding them. I just got new bleeder screws with dust caps for $3 and it's all good.

I’ve never had any issues either - I always use Techstream to bleed the brakes, which takes 5 minutes max to do all 4 corners - but many others on MUD have reported issues bleeding the rears.

 

[jmcboots]

Follow up for everyone if someone should stumble across this post.

I got the resonators in the other day and did the VSC ECU repair. Worked like a charm! Easy job if you can solder.

I did the 40 pedal thing and that got the ABS motor spinning again.

Then once I had both of those I was able to bleed everything with techstream.

Thanks to everyone who chimed in, I really appreciate you guys and this whole site for the massive wealth of knowledge here.