Anti Slip light coming on

[Village Idiot]

Hi All, new RX400h owner from Gloucestershire here.  Never had a Lexus before, my friend bought a RX300 and I was very impressed so took the plunge.

I've got a 2006 example with only 56k miles in awesome condition.  I've noticed however that under braking sometimes the anti slip light starts flashing.  There's certainly no slipping going on as it was under dry conditions on a flat road in a straight line.  Any thoughts as to the cause?  I'm guessing (hoping) that it's a sensor somewhere not playing.  

Also I've noticed that under braking the brakes seem to feel like they're grabbing and letting go slightly every few seconds, not like abs, but like its trying to adjust something, which could be related to the above issue I guess.  The discs and pads were replaced 10 months ago and have covered 4k miles since.  

Any  suggestions most welcome

cheers, Paul

[Britprius]

Hi Paul. 

Welcome to LOC. I know this may sound very basic, but we have to start somewhere. Are all the tyres the same size, and across each axle are the tread depths similar with even tyre pressures?

If everything is ok on the tyre front it does sound like you have an ABS sensor or reluctor ring problem. Closely inspect the reluctor rings for missing teeth, excessive rust, or a split in one of the rings. The rings are mounted on the outer ends of the drive shafts, and take the form of a ring with external teeth. A sensor counts each tooth as it passes with wheel rotation.

John.

[Village Idiot]

Thanks John,  The front tyres were replaced by the previous owner as part of the sale, the rears had good tread and they are matching tyre make and model, so there definitely is more tread on the fronts, but not much.  The ABS sensor and reluctor ring theory sounds interesting, I shall investigate, thanks for the info! 

 

 

[Rutlandlex]

That's very weird.  Normally the anti-skid light would come on under acceleration i.e. traction control or if the car was in a spin.  My guess would be that the car thinks that you are in a spin and it is possibly pulsing each brake in turn trying to find the best grip.

I'm guessing that you're not driving in this way so I would imagine that one wheel is registering as going slower or faster than it really is hence confusing it.  I would say wheel speed sensor/ABS sensor or reluctor ring as already suggested.

[Britprius]

1 hour ago, Village Idiot said:

Thanks John,  The front tyres were replaced by the previous owner as part of the sale, the rears had good tread and they are matching tyre make and model, so there definitely is more tread on the fronts, but not much.  The ABS sensor and reluctor ring theory sounds interesting, I shall investigate, thanks for the info! 

 

 

Have you checked the actual tyre sizes fitted on each wheel of the car? They should all be the same.
 It has been known for a different width or aspect ratio to be inadvertently be fitted. This gives a different TPM (turns per mile) for the wrongly fitted tyre fooling the anti skid system into thinking there is a problem.

John. 

[Hangie]

Have you checked brake fluid level ? Normally it would use different indicator but who knows and check is simple 🙂

[Village Idiot]

Update:

Actually got a "check VSC" error so decided to take it to Lexus Cheltenham as they have a good reputation around these parts.  Turns out the front drivers side reluctor ring is cracked - excellent diagnosis britprius!   The best bit was that Lexus said that I would need to replace the whole drive shaft as they cannot order the reluctor ring as a separate part!  After I stopped laughing I requested that they kindly put everything back together and give me the car back.  Spoken to my usual independent garage who are happy to replace the ring on it's own but I have to supply the part.  Question is, where is the best place to get it?  I've seen them on eBay but not entirely sure of the quality.    

Radical thinking now - Is it an easy DIY job? 

 

 

[Britprius]

Replacing a reluctor ring is within the realms of the average DIY requiring removing the drive shaft nut, and wheel hub to expose the drive shaft end, and reluctor ring.
If the old ring is cracked it will just pull off with your fingers. It is then a matter of cleaning the drive shaft surface and tapping on squarely the new reluctor ring. If the new ring is not very tight on the shaft apply some bearing fit to the mating surfaces.
Bearing fit is is a compound that as it dries expands.

eBay is the place to get the rings. Check the inside diameter, and the number of teeth for correct fit.

John 

[Village Idiot]

Update:  The troublesome reluctor ring has now been replaced with an £18 eBay part.  Local garage changed 1.25 hours labour and I'm happy to report that all symptoms have been fixed, no anti-slip light under braking and brake pedal is nice and smooth as it should be.  This is why I like owner forums! Case closed.

Now to do something about that Victorian sound system...…...

[Britprius]

1 hour ago, Village Idiot said:

Update:  The troublesome reluctor ring has now been replaced with an £18 ebay part.  Local garage changed 1.25 hours labour and I'm happy to report that all symptoms have been fixed, no anti-slip light under braking and brake pedal is nice and smooth as it should be.  This is why I like owner forums! Case closed.

Now to do something about that Victorian sound system...…...

Pleased to hear your problem is now fixed.
I feel it is somewhat of rip off that Lexus do not supply some of the smaller component parts costing perhaps a few pounds for there cars, and instead only sell complete assemblies costing many hundred sometimes thousands of pounds. 
The list may be added to, but here is some items I know of.

Ride height and headlamp adjuster links that snap due to seized ball joints.  You have to buy the complete sensor costing £150 upwards.
Reluctor rings. You have to buy complete drive shafts at many hundred pounds.
Gearbox oil pump bearings "less than £10". you have to buy a complete pump at an eye watering £2500.
Traction Battery replacement modules. You have to buy a complete Battery. Again circa £2000 plus.
LED rear light units sealed so you cannot replace faulty LED's. I had a Prius where all the other lights were bulbs, and could be changed except the stop lamp. Cost £186. Ok not strictly Lexus, but the same stable Toyota.

I know to some degree all manufactures do this, but that in it's self does not make it right.

John.