Yaris 2004: ABS issue

[YarisPie]

Hello. I've had an ABS issue on my French-built Yaris hatchback aut 1.3 2004 for a good while now.

Issue

- The ABS system kicks in during slow rolls with light pressure on the brake pedal.

To rule out the rear
- A few weeks ago I got both rear wheel bearings changed; it had no effect on the ABS issue. The bearings had to be changed anyway.

Visual inspection

- Last weekend I inspected both front sensor cables for cracks or outer wear. 
I noticed that the left one had the number 89543-0D010 in white and the right one had the number 89542-0D010 in yellow.

Question

- Since one is white and one is yellow, does it indicate which one is the sensor OEM? Or are the different colors irrelevant?

Also, the left one looked way newer compared to the right one.

So far

- Been to multiple garages that used different scan tools on the car without being able to tell which wheel is causing the issue. 

Other

- Two garages also inspected the tone rings and told me they were completely fine.

I've had the issue with both of my OEM Yaris wheels with nearly new and balaced tires.

I've also changed front and rear brake pads about 6 months ago.

Trying to figure out which front side to focus on first. Thanks!

[TonyHSD]

What brand rear wheel hubs have you fitted? 
Do not rule out these because they might have turn to be the main cause of an issue. What faults are displayed on your mechanics scan tools? This is important to start your fault finding. 

[Bper]

Hi,The different colours on the sensor cables white and yellow likely do not indicate which is the OEM sensor. They may be part numbers or markings used by Toyota.

Since the left sensor appears newer than the right one, it might be worth checking the right side, especially since you've already had the left sensor inspected and replaced. The issue you describe, with the ABS kicking in at low speeds, often points to a faulty wheel speed sensor or an issue with the tone ring. If the tone rings are ok and you have had both sensors checked, the right sensor might be worth looking at further, or replacing it with a known good one.

Its possible the issue could also be the ABS control module,it may not be correctly be interpreting the signals from the sensors, especially if the diagnostics tools were unable to pinpoint the problem. 👍

 

[flash22]

LH - 89543-0D010

RH - 89542-0D010

 

Back to basics

Do a flash test

Link the pins shown below, turn on the ignition and count the flashes of the ABS light it will be a 2 digits 1st number then a pause followed by the 2nd, it will either repeat the code or go to the next code

 

Edit. i take its a MMT (automated manual) car

 

[YarisPie]

5 hours ago, TonyHSD said:

What brand rear wheel hubs have you fitted? 
Do not rule out these because they might have turn to be the main cause of an issue. What faults are displayed on your mechanics scan tools? This is important to start your fault finding. 

I can't remember from the top of my head, but I can look it up. Although the ABS issue started about 9 months prior to changing the bearings.

5 hours ago, Bper said:

Since the left sensor appears newer than the right one, it might be worth checking the right side, especially since you've already had the left sensor inspected and replaced. The issue you describe, with the ABS kicking in at low speeds, often points to a faulty wheel speed sensor or an issue with the tone ring.

I'm suspecting that the left one has been replaced at some point before I bought the car, but I'm not totally sure. It sounds wise to start with the right one.

I have been noticing the speedometer being jumpy and quite inaccurate at low speeds. It's not unusual that the displayen speed is stuck at like 8 km/h and then jumps down to 3 or gets stuck at 5 km/h then makes a quick jump to 11. Might be something to that?

3 hours ago, flash22 said:

LH - 89543-0D010

RH - 89542-0D010

Back to basics

Do a flash test

 

That sounds far from basic—at least to me. I'm not a mechanic of any sort, but I get a feeling I might need some sort of scan tool to sort that out?

[talldave]

Hi - I've had the same problem on my 1998 Avensis 1.8 petrol 7AFE auto for a couple of years now and haven't been able to locate the problem so I've just lived with it.

flash22 - I'm familiar with doing the flash test that you mention (I've done this previously when the engine management light (EML) came on - it was the O2 sensor that needed replacing then). What codes would I be looking for and what would they tell me? Can I use the same pin linking as in your diagram? There are no dashboard lights on now - neither EML or ABS. Thanks.

[talldave]

Following on from my previous post...

From a document I found when I did the flash test previously, I see that the pin linking is the same on  my Avensis (i.e. link pins 4 and 13).

I see also that code 42 is "Speed sensor" - is this the wheel sensor? If so, how do I know which wheel is the problem?