ABS coming on

[Alpine]

Hello, my ABS has come on a few times when braking, when it shouldn't

I had the same issue on a Toyota and I had to change the ABS rings on the driveshafts as they were corroded

Is it a similar set up on the V70, and are they a known weak point?

[Luxobarge]

So as I understand your post, you're saying that you don't have an ABS error light on the dash, but that the ABS is activating when the brake pedal is pressed, but doing it when it shouldn't?

If so, then yes, the ABS rings on the front are probably either corroded or cracked. Yes, it's relatively common on these, not too difficult a job provided you can get the hub spline out of the wheel bearing OK, you'll have trouble doing this without a puller unless they've been removed before. Much easier to replace the rings if you take out the whole driveshaft or at least the CV joint and do it on the bench. A good time to also replace the CV joint boots too if they're looking tired. Also worth checking the wheel bearings in case they are also getting tired, as it's the same job to change them too.

ABS rings are really cheap and easy to get hold of, so main issue here is labour time.

I did all the above not long ago on mine, not too bad a job but a bit time consuming.

other VERY common fault on these is broken solder joints on the ABS module - a much easier job IMHO but I'd say your symptoms don't tie in with this as broken solder joints usually put the ABS light on.

Hope this helps!

[Alpine]

Originally Posted by Luxobarge

So as I understand your post, you're saying that you don't have an ABS error light on the dash, but that the ABS is activating when the brake pedal is pressed, but doing it when it shouldn't?

If so, then yes, the ABS rings on the front are probably either corroded or cracked. Yes, it's relatively common on these, not too difficult a job provided you can get the hub spline out of the wheel bearing OK, you'll have trouble doing this without a puller unless they've been removed before. Much easier to replace the rings if you take out the whole driveshaft or at least the CV joint and do it on the bench. A good time to also replace the CV joint boots too if they're looking tired. Also worth checking the wheel bearings in case they are also getting tired, as it's the same job to change them too.

ABS rings are really cheap and easy to get hold of, so main issue here is labour time.

I did all the above not long ago on mine, not too bad a job but a bit time consuming.

other VERY common fault on these is broken solder joints on the ABS module - a much easier job IMHO but I'd say your symptoms don't tie in with this as broken solder joints usually put the ABS light on.

Hope this helps!

many thanks, yes first bit is right, I'll look to get some rings

[liammedler]

Does the temperature affect when the ABS is activated/when the light comes on? I found that in very low temperatures the ABS light would stay off but anything above -2deg the light would come on. I found this was the hairline cracks in the ABS ECU soldered joints. After a session with a soldering iron it was sorted

[Luxobarge]

Originally Posted by liammedler

Does the temperature affect when the ABS is activated/when the light comes on? I found that in very low temperatures the ABS light would stay off but anything above -2deg the light would come on. I found this was the hairline cracks in the ABS ECU soldered joints. After a session with a soldering iron it was sorted

He's saying that the light doesn't come on at all, just that the ABS activates under normal braking, i.e. the wheels are not skidding, but the ABS module thinks they are. This is usually due to messy or missing signals from the sensors due to corrupted and poor reading of the spikes on the reluctor rings, which in turn is usually due to corrosion or cracking.

Because the ABS light is NOT coming on, I doubt that it's the soldered joints in the ABS unit on this occasion. It's perfectly possible, but rare to have that problem and NOT see the ABS light.

[Tannaton]

If it's only doing it when warm then 90% likely a faulty ABS speed sensor - if you have VIDA or suitable diagnostic read the live data from all 4 sensors and see which one drops out.

If it wasn't temperature dependent i would be saying cracked ABS ring.

Sound advice from Luxobarge above, the lack of ABS light means system working normally, other than thinking one wheel keeps stopping.