2000 LX 470 - New accumulator/motor wont pressurize

[rainmann97]

I replaced the accumulator and booster pump with one from City Racer. I got the whole thing put back together and attempted to begin bleeding the brakes. I pumped the pedal 40 times, then turned the key. The pump doesn't run for 30ish seconds like its meant to... it runs for a few seconds at a time and then turns off. This cycle then repeats.

I've repeated the pump pedal 40x and key on several times with the same result. I don't know what I'm missing here. Is there some kind of electronic control that's causing this? Did a miss a bench bleeding step? Or perhaps my master cylinder itself has failed in some way (I only replaced the accumulator/pump because of limited budget) My issue before seemed to be the accumulator (link to my previous thread: 2000 LX470 - ABS motor constantly running, with pulsing brake fluid level - https://forum.ih8mud.com/threads/2000-lx470-abs-motor-constantly-running-with-pulsing-brake-fluid-level.1359453/#post-15904872)

Any help is much appreciated!

 

[rainmann97]

I was able to pull the ABS codes.
C1241
C1223
C1252
C1256

The C1241 high/low voltage seems like it needs to be resolved before I can really try to diag anything else.

 

[Project Garage]

I replaced the accumulator and booster pump with one from City Racer. I got the whole thing put back together and attempted to begin bleeding the brakes. I pumped the pedal 40 times, then turned the key. The pump doesn't run for 30ish seconds like its meant to... it runs for a few seconds at a time and then turns off. This cycle then repeats.

I've repeated the pump pedal 40x and key on several times with the same result. I don't know what I'm missing here. Is there some kind of electronic control that's causing this? Did a miss a bench bleeding step? Or perhaps my master cylinder itself has failed in some way (I only replaced the accumulator/pump because of limited budget) My issue before seemed to be the accumulator (link to my previous thread: 2000 LX470 - ABS motor constantly running, with pulsing brake fluid level - https://forum.ih8mud.com/threads/2000-lx470-abs-motor-constantly-running-with-pulsing-brake-fluid-level.1359453/#post-15904872)

Any help is much appreciated!

Hi there it's brad from AUS I recently replaced my misses pump/fluid pump on her hzj105 and reused the accumulator, I found it super difficult to bleed it and had me scratching my head for a few seconds but I ended up working out how to in car bench bleed it , this is what worked for me remove the accumulator completely and remove the spring and seat them turn the ignition key on and the pump will run for around 3 seconds and shut off , repeat the process you may need to do this around 10-30 times until you start to see the fluid pump out it will just trickle out with a lot of air bubbles then once you have gotten to the point it's starting to push a lot of volume of fluid out and minimal air bubbles then refit the accumulator and crack the red outlet line and keep repeating the ignition key on off cycle and you will see the last of the air push out the line fitting once you are pretty confident that 95% of the air is out then tighten the line back up , then keep turning the ignition on and off every time the pump cuts out after a few seconds cycle the key again and just keep forcing it to charge the accumulator once it starts to build pressure you will find the abs and handbrake light will go away and the pump will then work as normal then you will proceed to do a normal brake fluid flush until any air that's in the lines are out keep the brake fluid level super high because your going to pump alot of fluid to get all the air bubbles out , I used around 2.5L to bleed the air out then also bleed the brakes . Hopefully this helps

 

[Rusted100]

I have a 99 100 series which has been having brake problems for a while. Pump seems to run every time I would hit the brakes kind of whines at the end before it shuts off. Eventually I think it just gave up and died replaced the master cylinder with a used one. Pump still runs all the time. Still whine just before shuts off. Lots of fluid comes out of bleeders with pump on but can't get any with ignition off just pumping pedal. Have tried to do bench bleed on vehicle connecting all MC lines back into reservoir. Got some bubbles but it didn't fix it. Thinking may be electrical but not sure how to diagnose that. The sunroof leaks so it's getting wet inside sometimes. Have replaced most of the lines and can't see any leaks. Not sure what rainmann meant in above post about removing accumulator spring and seat.

 

[rainmann97]

Issue resolved. Hopefully this might help someone in the future.

I ultimately did replace the mc/booster with a new oem part. This however did not fix the issue. Upon turning key on, the pump would still run for only few seconds at a time, and not build pressure. On a whim, I ordered a used abs ecu (89540-60150) from ebay (shipped from UAE). Swapping this in immediately fixed the issue. My gut all along was that the mc/booster was not the issue, and I should have listened to my gut, but I allowed myself to be swayed by all the comments on this forum about MC/booster replacement. Future readers with my same issue, I highly encourage you to consider the abs ecu if your pump will not run for more than a few seconds at a time. It would be very easy to borrow one from a friend or club member to test.

Ultimately I fixed the issue by throwing parts at it. I'm not proud that it took an unnecessary $1400 part to figure it out (oh well, the mc had over 250k and was probably due to fail anyway), but I am not a professional diagnostician with enough knowledge of electronics to know how the issue would have been properly diagnosed without throwing the ecu part at it.