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Today at Atelier Kaz - Private NSX Enthusiast, ex-Honda R&D engineer with F1, Indy/CART background

ABS Service 02

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As reported in ĎABS Service 01í, three out of four solenoids on this NSX were stuck closed.

Good news (or bad news, from a certain point of view) is, unlike many other ABS issues, this wonít trigger the ABS warning light and it won't disable the ABS.

However, as they are stuck closed, they wonít be able to release the brake pressure and thus, no ABS control at all on the three out of four tyres.

Somewhat dangerous as there is no ABS warning light to tell the driver that the ABS is not working.

Tried several different methods to recover the three solenoids without any success.

So, during the test driving session and to/from the alignment place, exercised the ABS many times to flush the solenoids under vibration.

Good news.

Managed to recover two faulty solenoids with the above method so just one left.

For the last faulty solenoid, used the back pressure flush method by activating the solenoid while operating the pump at higher pressure.

Finally, all four solenoids started to return the fluid to the reservoir.

As all three solenoids were stuck for many years, I am not 100% happy with one of the solenoids as it doesnít close quick enough so will keep flushing all four of them every day until the owner collect his NSX.

Click image for larger version. 

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As you heard from many owners, if you donít flush your ABS modulator and solenoids at a certain interval, it will eventually trap some air and get leaky resulting in foamed fluid overflowing out of the reservoir like this.

Another ABS recovered.


Updated 25-07-2011 at 08:07 PM by Kaz-kzukNA1

ABS Original


  1. 's Avatar
    Hi Kaz,

    I'm currently in the process of flushing my ABS / solenoids (whilst my car is missing a shock absorber!) and removing the odd bits of debris. Whilst doing this process, what are the signs of any problems?

    The 2 I've done so far seem to flow into the reservoir at a pretty quick rate and seem to switch on and off fine. Anything I should check for?


  2. Kaz-kzukNA1's Avatar
    Hi, Ed.

    I was hoping that you were enjoying your lovely NSX under the hot British summer but looks like it is off the road at the moment.....

    Regarding your question, it depends on the spec of your ABS but if I remember correctly, your NSX was equipped with 1st generation system.

    You can distinguish the 1st and 2nd generation by the shape of the reservoir.

    Please have a look at the 1st and 2nd photos in the ‘ABS History’ at the ‘Brake’ section of my ‘NSX Technical and Service information Index’ thread that you can find at the right side bar.

    As you can see, the reservoir on the 1st generation is pretty much just a square box shape whereas the 2nd generation one has partial protrude/extension piece.

    As you seem to know the basic procedure, I’m going to simplify the process and explanation.

    First, please release the high pressure brake fluid from the accumulator using the ABS SST or other method.

    Replace the brake fluid inside the reservoir with the fresh one and then pressurise the system by manually overriding the ABS pump.

    During this process, keep eye on the fluid return port inside the reservoir.

    You should not see any tiny bubbles or fluid movement from the return port.

    Please do not confuse this with the fluid sucked into the pump from the reservoir.

    You may want to place your finger close to the return port to actually feel for the fluid movement from there.

    If you see or feel something, you have a leaky solenoid.

    Disconnect all four solenoid connecters.

    Connect BLK wire to the GND and apply +12V to the RED wire in short burst of on/off mode.

    You should see the fluid coming out of the return port ONLY during the +12V was applied.

    If you see any fluid coming out of the port even AFTER disconnecting the +12V from RED wire, you have a leaky solenoid.

    If you hear a single click when +12V was applied but no fluid coming out of the return port, your solenoid is stuck closed.

    If that was the case, try flushing the solenoid while building up the pressure by activating the ABS pump.

    Updated 03-08-2011 at 11:05 PM by Kaz-kzukNA1 (Too many spaces)
  3. 's Avatar
    Thanks for the info. I believe in this case that the ABS system is in good working order.

    Just got the shock absorber back on the car and removed the O2 sensors ready for replacement. Was a lot easier than I thought it would be, just removed the O2 sensors after turning the engine off so the manifolds were hot. Waiting until Monday to get a M18 x 1.5mm thread chaser to clean up the threads before installing the new O2 sensors. Then in for MOT & tax during the week.
  4. Kaz-kzukNA1's Avatar
    Hi, Ed.
    If you are replacing the O2 sensor, please first read any error code ( stored on any of the controllers.

    Warm up the engine and then reset the ECU.

    Re-start the engine without touching the TH pedal or applying any electrical load such as A/C, light, etc and keep the engine at idle rpm for about 15min.

    Stop the engine, restart and go out for some driving session.

    It will take some time to re-learn the shorter and longer term fuel timer coefficient so be careful with the timing of doing this especially if you are having MOT soon but since your NSX is non-OBD2 car and under UK test procedure, probably won't be too much of issue.

  5. 's Avatar
    Thought I'd just let you know that the MOT was fine. I think the CO reading was about 0.2 (limit 0.3) whereas last year it was 3.0+. My car's registration date has slipped back to 31/12/92 due to some computer system change with the dvla so it gets CAT tested even though it was actually registered in January 92. I will again try and get this fixed. I guess I could put a K reg plate on the car with their mistake

    It may have passed purely due to the fact I gave the car a good hard drive before the MOT and I presume they tested the emissions within 30 mins or so after I dropped off the car. I asked how he tested it last year and he had only warmed it up by idling and I had only driven it 5 mins to the garage.

    The old O2 sensors were only about 4 years old I think when Kevin replaced the manifolds. Either way the car is running very smoothly and I was able to get rid of an extender cable which came with the manifolds as one of the new cables were longer than the old. Also they were pretty cheap from the USA and came within 48 hours of ordering.