Unnecessary ABS operation

ComicGeek

It's a Toyota Rav 4 Hybrid, nearly 2 years old, had from new. Suddenly after driving the same roads for nearly 2 years in it I am getting ABS operating when braking from less than 10 mph to a complete stop. Not every time or in the same place, but a couple of times a day every few days. Slip indicator comes on the dash, audible alarm and then I feel the pulsation through the brake pedal. Doesn't happen when braking heavier, only at low speeds.

No gravel on the road, has been very dry conditions apart from today, no change in driving style or heavy braking.

Have taken it into a Toyota garage today for them to look at - computer log shows no previous ABS operation until a month ago, with multiple operations each week from then.

Toyota are saying that there's no problem and nothing they can check without physically driving it around to replicate the ABS operation. It just sounds a bit suspect to me that there's never been an ABS operation in the proceeding 21 months, and now on average 4-5 a week in the past month.

Any ideas/experience on what it can be, or what I could be asking Toyota to look at? It is worrying me as it increases my stopping distance slightly when operating.

big_mortgage

Well I had an Aygo that would always activate the ABS on one particularly lumpy (not pot holes, like tiny mini hills) bit of road coming up to a mini roundabout. This would have been about 15-0 mph so not fast and very gently braking. Perhaps the piece of road you have been driving on has worn a bit in the last two years and the profile has changed?

Test on a very smooth piece of road and try to replicate all the other conditions?

debtdebt

Tyres worn perhaps?

ComicGeek

It's never the same location or road type that it activates - the only constant is that it's breaking from low speed to standstill, but it's intermittent and I can never replicate it when trying.

Tyres are fine, still got 7 on rears and 6.5 on fronts. Steering, suspension, brakes, tracking all recently checked and also fine. Just seems to me that the ABS is getting a false signal to operate occasionally.

ComicGeek

Just checking the wording on the mechanics report from Toyota today, and they've noted that ABS has been operating 'frequently' recently, so perhaps I'll try and speak directly with the mechanic and see what they say.

Lorian

Visually inspect the driveshafts for a damaged/split ABS reluctor ring.

sebloak

Probably an ABS Sensor failing. Had the same thing with a ford KA, always at random, low speed and no dash warning lights lit. Mechanic also couldn't find anything until I took it back in when the ABS light came on a couple of months later. 1 new front sensor cured it.

ComicGeek

Thanks for the replies - 2 yr service is due in a couple of weeks, so I'll check what the latest logs are then and get them to check the sensors and reluctor rings as suggested.

victor2

sebloak wrote: »

Probably an ABS Sensor failing. Had the same thing with a ford KA, always at random, low speed and no dash warning lights lit. Mechanic also couldn't find anything until I took it back in when the ABS light came on a couple of months later. 1 new front sensor cured it.

I second that. Had the same issue with a Mondeo many years back. Until brake system warning lights came on and I was able to get it to a dealer with the lights on, did they find the problem to be one wheel sensor.

ComicGeek

sebloak wrote: »

Probably an ABS Sensor failing. Had the same thing with a ford KA, always at random, low speed and no dash warning lights lit. Mechanic also couldn't find anything until I took it back in when the ABS light came on a couple of months later. 1 new front sensor cured it.

victor2 wrote: »

I second that. Had the same issue with a Mondeo many years back. Until brake system warning lights came on and I was able to get it to a dealer with the lights on, did they find the problem to be one wheel sensor.

That does annoy me - doing a google search on this shows it to be a relatively common issue, so should be something that the garage could check with me having to do my own research.

Just because the car is less than 2 years doesn't mean that a sensor can't fail, so I'm annoyed that the servicing manager said there wasn't anything that they could check....