Low Speed ABS issues on RX300 year 2000.

[PUKU]

 

All wheel speed sensors have been checked/changed as appropriate (Lexus OEM)- no true faults found apart from dirt on the reluctor rings. The ABS pump and the ECU have been changed - no change in operation. So now attention to the only thing left that I know of is the gear box speed sensor(s) Looked through the OEM workshop manual ... there are TWO speed sensors on the gear box, found under the Air Cleaner assy.. one is called a TURBINE Speed sensor and the other is the COUNTER Gear speed sensor ... Neither sensor has shown up in diagnostics.

Anyone experienced issues with the gear box sensors (which one?) and/or slow speed (15-12mph) ABS actuating causing a judder and loss of brakes?

[Delphius1]

Techstream might be of use here as it's able to dig deeper into the ABS system and check out the brakes, if necessary you can run active tests of the ABS system and Techstream will report back any issues. 

I know you say you've changed the ABS module, but did you change the electronic part, the valve block or both parts of the ABS module together. Also, did you use Techstream or something similar to actively bleed the brakes once the ABS module was changed? There's a procedure in Techstream that you need to go through once the ABS module has been changed. It activates the ABS pump to pressurise and actively bleed each brake circuit in turn. It pumps brake fluid through the ABS valve block to each caliper in turn.

There is a YouTube video about it somewhere, I'm sure I've seen it.

[PUKU]

The complete ABS module/pump was changed, and my first reaction was that the symptoms are exactly the same. I do not have Techstream but bleeding took the form of doing two handed (footed!) the old fashion way starting at the module bleed nipple then rears then fronts. The process was carried over two days (my own time restrictions) prior to road testing with the outcome being exactly the same as before, nothing changed in any way, apart from my own thoughts and findings over the past year or so that it only happens at very low speed to stop.

Lexus Service couldn't find it!

I will now try changing the speed sensors on the gear box. I could buy two and change both but i would prefer to do one at a time to determine which is what! My thoughts are to change the COUNTER GEAR SPEED SENSOR first the other one (INPUT TURBINE SPEED SENSOR) sounds to me if it is associated with gear changing.

Any thoughts here?

As a further observation both sensors LOOK identical from the outside. Becoming familiar with Lexus thinking now; as they are identical and not handed in any way, can I safely assume they are both the same part number?

[PUKU]

Just another though, would the oil be at fault. It is a 2000 vehicle, with around 130k. I had the car at 30k and transmission oil has not been changed.

[steve2006]

I know you checked the reluctor rings previously but did you check for cracked ones which is a fairly common problem?

[Herbie]

2 hours ago, PUKU said:

I do not have Techstream but bleeding took the form of doing two handed (footed!) the old fashion way starting at the module bleed nipple then rears then fronts

Before throwing any more money and time at it I think I'd be getting Techstream on the job because it may just do things that you haven't. There may be a fellow club member near you who has it and who would be willing to help.

[PUKU]

I am still struggling to get this Low speed issue with ABS kicking in solved.  I have also found out that it is a common fault with LEXUS so why is there no solution published The GS 300 and RS 300 and other have the same problem.

Is there anyone near Dorset having the same problem?

I have now changed all Wheel speed sensors, some reluctor rings, the two speed sensors in the gear box, The ECU and the ABS pump.

What's left?

[PUKU]

I am at the stage near to scrapping the car or better still finding someone with the knowhow to disable/delete the ABS facility all together from the car.

Anyone?

Having driven professionally for over 60 years approx. 50-60k miles per year without ABS I certainly don't need it now!

[Herbie]

Have you interrogated the live data/freeze frame using Techstream?

[PUKU]

I don't have Techstream, but a my Autel doesn't show anything nor other OBDII readers. All they show is all wheels doing the same speed!

[ColinBarber]

5 hours ago, PUKU said:

I am still struggling to get this Low speed issue with ABS kicking in solved.  I have also found out that it is a common fault with LEXUS so why is there no solution published The GS 300 and RS 300 and other have the same problem.

because it isn't a common fault.

[ColinBarber]

Have you properly checked the speed sensors are operating correctly using a scope? Correct voltage, no excessive noise etc.

[PUKU]

I am afraid I do not have the TechStream or an oscilloscope! 

If there is any one out there in the area that has a trip would be worthwhile I am sure.