ABS issues

[Papalazarou]

Thanks Kaz,

I drove the car today to see exactly how it reacted to different braking input.
Driving from cold and applying a small amount of braking force, triggered the chirping and the pedal to feel as if the ABS had been triggered when it had not; so kick-back and the feeling of the pedal falling through its travel.
At low to medium speeds the chirping would kick in regularly when not using the brakes.
At higher speeds with higher braking force, the brakes worked fine, but would chirp and kick when I backed off the brakes but was still applying some pressure.
Overall the kick was quite strong, but most disconcerting was the clunk as the pedal would fall through it’s travel as though I had lost traction.
The picture is the invoice for the seals replaced at the time of the rebuild.
Apparently when everything had been rebuilt/replaced, the previous owner reported that the ABS was improved, but still displayed the above characteristics at times.

[Kaz-kzukNA1]

I now understood why you were using the word ‘chirping’ unlike many owners referring the ABS pump noise as ‘squeaking’, ‘rattling’, etc.

Your issue is not the ABS.
It’s the wheel speed sensor signal quality (noise) issue.

You may still have certain ABS issue but from your test driving report, it’s doing what it should.

It explains the chirping and not squeaking noise plus the reason for the sunk brake pedal.
It will trigger the ABS light from time to time due to ABS pump continuously operating while the solenoid releasing the fluid back to the reservoir before accumulator reaching the targetted pressure.
In my personal view, classic ABS has design flaw.

Experienced exactly the same thing on few NSX with the classic ABS.
I still remember how scary it was drivng such NSX for the first time.

Later, it also happened on my NSX but with the upgraded ABS that I had better picture on what was going on.

This is what I reported at that time;
http://www.nsxcb.co.uk/entry.php?85-...and-14)-Part-3


With the upgraded ABS brain power, it can detect this signal quality issue and will trigger the ABS code #12, 14, 16 or 18.
Thus, you'll get the ABS light.

Unfortunately, with the classic ABS, the brain power is not enough that it can’t detect this failure mode and thus, no error codes assigned.
Thus, no ABS light.

Unless you can monitor the sensor signal while driving, it’s hard to find which sensor has the noise issue.

The simple resistance check will show the normal reading.
Never tried but after driving the car to warm up the sensor and then applying lots and lots of cold spray over the sensor body ‘may’ highlight something.


For your reference, only few examples so not definite but so far, this sensor noise issue happened only at the front sensors.
Again, it can happen at the rear side as well so please take that into your consideration.


From your photo, as expected, part of the o-ring at the piston body and the solenoid were replaced during the overhaul but not all of them.
The ABS pump is indeed the whole lot, both the mechanical pump + the electrical motor so expensive.
Most likely you have some air at the piston chamber side.
The flushing method in the link in my last post won't be able to flush this side of the ABS.


As investment made by the previous owner into your existing ABS, you could try replacing the w/speed sensor (probably try the fronts first) and then evaluate the upgrade option.
You'll need to replace at least one sensor any way.
Or, go for the upgrade and let the system to detect the noisy sensor.


Kaz

[Papalazarou]

Thanks Kaz,
I did the flash error codes this morning and got the following;
36 on the ECL
AND
Four quick flashes and one long flash from the ALB. 14?
I had similar symptoms on my first NSX (96 car), but with the TCS ALB lights on.

[Kaz-kzukNA1]

Addition to the 7.5A CLOCK fuse, did you remove the 20A ALB2,3 one before you drove this morning?
If not, the ABS error code was from the past.

CEL #36 is for the TCFC command line between TCS and ECU on non-DBW model.

It can be triggered if you struggle to start the engine, main relay issue, IGSW issue, misfire, etc.

If you saw ABS + TCS lights with sudden misfire like cut due to w/speed sensor failure, CEL #36 can be triggered with or without the actual CEL on the dash.

No CEL on the dash but the code will be stored if detected only once within the one driving cycle.
For example, if you disconnected the TCS controller.

I always get CEL #36 but without the CEL because I disconnected the TCS controller like 25 years ago.


ABS #41 or officially, it’s referred as #4-1.

Front Right w/speed sensor open/short circuit.

However, it won’t be fixed on its own and since TCS gets the level converted w/speed signal through the ABS controller, it should have triggered the TCS light at the same time unless you already disconnected the TCS controller.

This is the reason why I touched on the ALB2,3 fuse at the beginning and if you didn’t see the TCS light, most likely, the code was from the past.

If you did reset the ABS by pulling the ALB2,3 fuse and subsequently got ABS #41 but without the TCS light, at least, you have something to look at for the cause of chirping issue.


Kaz