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ABS issue
JC - 26/12/18 at 11:23 AM

Hi all, and hope you all had a great Christmas!

Daughters 2005 Yaris has an ABS issue. Just as the car comes to a halt, the ABS activates. It seems to only happen if you are stopping gently, like you would in traffic or at a junction.

I replaced the front 2 sensors as they were easy to do - no change!

I replaced one of the rear sensors - they come as part of a complete hub and the wheel bearing was noisy so it needed doing anyway! Still no change. This job as an absolute bar steward to do as the old hub was well and truly attached!

I can replace the final rear hub in a few days - don’t really want to as it was such a PITAS on the other side.

Any suggestions as to what the fault might be, other than sensors?

Thanks

nero1701 - 26/12/18 at 11:47 AM

Possibly the abs system wasn't bled when brake fluid was changed?

Have you plugged it into a diagnostic computer?

obfripper - 26/12/18 at 12:50 PM

Check the front reluctor rings for corrosion/damage, if there is a tooth damaged or an incorrect gap you will get erroneous activation due to the signal change.
If the signal effect is only minor it will not trigger a fault code.

Dave

JC - 26/12/18 at 12:58 PM

Thanks - I’ll take a look at the rings.

It’s not been plugged into a diagnostic computer - I just checked using an OBD reader and there are no latched faults. Brakes not been bled for ages....

mcerd1 - 26/12/18 at 01:59 PM

quote:
Originally posted by JC
I just checked using an OBD reader and there are no latched faults


what kind of OBD reader ?

most of of the cheaper ones can't read ABS faults

Slimy38 - 26/12/18 at 03:06 PM

Are you sure it's the ABS? I didn't think ABS actually did anything at low speeds, below 15mph or so. Is it the light flashing or do you have the horrible groan/vibration of the ABS pulses? Could it be the pads vibrating in the calipers rather than full blown ABS kicking in?

NigeEss - 26/12/18 at 05:10 PM

I'd also vote for a broken reluctor ring.

JC - 26/12/18 at 05:11 PM

Definitely ABS - you can feel it through the pedal and hear it working...

ian locostzx9rc2 - 26/12/18 at 08:13 PM

I second the above post cracked abs ring would be easy to see if a diagnosic machine was plugged in and easy to spot on the front ones

[Edited on 26/12/18 by ian locostzx9rc2]

adithorp - 26/12/18 at 08:45 PM

quote:
Originally posted by obfripper
Check the front reluctor rings for corrosion/damage, if there is a tooth damaged or an incorrect gap you will get erroneous activation due to the signal change.
If the signal effect is only minor it will not trigger a fault code.

Dave


+1 or a split rrluctor ring that can spin on the CV joint.

rusty nuts - 27/12/18 at 10:17 AM

Have you checked the brakes themselves? A stick calliper/pad can cause enough of a brake imbalance to activate the ABS . Might be worth stripping the front brakes to check and clean , make sure everything is working as it should. A split or broken reluctor ring is more likely to show up a permanent fault with the warning light .

JC - 27/12/18 at 04:34 PM

Ok, checked the reluctor rings - the odd slight bit of corrosion but didn’t appear broken. Both sensors had flakes of rusty metal on the tips though, and the teeth on one of the rings were shiny and looked like they might be catching somewhere.

The sands of time have run out for me tho - back to work for a couple of weeks so it’ll have to go to the local non-franchise Toyota man to see how much he wants to charge me to fix it

Thanks for all the help. I’ll post the answer when I know it

obfripper - 27/12/18 at 10:13 PM

quote:
Originally posted by JC
Ok, checked the reluctor rings - the odd slight bit of corrosion but didn’t appear broken. Both sensors had flakes of rusty metal on the tips though, and the teeth on one of the rings were shiny and looked like they might be catching somewhere.

The sands of time have run out for me tho - back to work for a couple of weeks so it’ll have to go to the local non-franchise Toyota man to see how much he wants to charge me to fix it

Thanks for all the help. I’ll post the answer when I know it



If you look under the shiny teeth you will find corrosion between the ring and cv joint casing that has pushed the ring out of round, the ring is hitting the abs sensor causing the shiny teeth and the erratic signal.
The ring is likely to be permanently damaged, but there are some replacement rings available on ebay which saves replacing the complete cv joint - you will need to know the joint diameter and number of teeth to match up a replacement.

Dave

JC - 3/1/19 at 05:09 PM

Fixed!!!!

The hub was corroded where the ABS sensor slots in, which was stopping it reading correctly! Lots of rust cleaned back so that the sensor sits flush and square and job done!! Hurray!

Thanks everyone!

britishtrident - 3/1/19 at 07:11 PM

You got of lightly playing ABS parts roulette can be very expensive same goes for air bag faults.
These days it really pays to get a scantool that will work in manufacturer mode and at read and clear faults beyon the ken of basic OBD2.

https://www.ebay.co.uk/itm/Autel-MD802-DS-Model-OBD2-Car-Code-Scanner-Airbag-ABS-EPB-Oil-Reset-EU-Version/232874139798?hash=item3638616096:g:QPYAAOSwW B5b5qd1:rk:43:pf:0

[Edited on 3/1/19 by britishtrident]