Hi all,

last night after changing my rear wheelbearings I got an ABS failure.
Also when I push hard on my brake pedal it seems that I can push it deeper and deeper.
What can be the solution to my problems?

Greetings
Frank

ps. yes I have the bearings for the ABS sytem with the magneto on it.

But have you fitted them correctly ..that is the question and why you have the problem :chin:

@ PNL

In my humble opinion I fitted the bearings the same way the old ones came off.

Your right why have I now problems with the ABS?

Frank

Soft pedal would suggest (to me at least) low pressure in the brake system somewhere. Presumably you just lifted the calipers off without disconnecting them completely when you did the bearings

I'd check your fluid levels first, start her up and get someone to pump the brakes with the cover off the reservoir, if it needs a top up take it to the 'max'. If it's still soft after a fill up and the system 'pumped' then it's possible there's some air in there somewhere. So a brake bleeding exercise is called for.

You might try disconnecting the battery and leaving it for an hour then reconnecting and see if your ABS failure was a phantom indication rather than a proper failure as it should reset..... maybe.

The bearing set was propably delivered with an integrated ABS ring. Did you use the fantastic magnet detector to decide which side of the bearing to be mounted facing the sensor?

M.

@ Morty Mort,

Help me if you can I don't understand what you mean?

Frank

For ABS to work it needs to know the rpm of each wheel so in each wheel hub there is an rpm sensor device. On the Stilo there is a magnetic pattern embedded in the wheel bearing and an external sensor which picks up the wheel rotation speed from the magnetic ring.

Make sure you haven't done something obvious like forget to reconnect the ABS sensor wire and double check the connector anyway

If you connect a multimeter to the abs connector and spin the wheel then you should see the voltage fluctuate


It's easy to install a bearing wrongly (damage, fit wrong way around etc) and then the ABS won't work


Re the brake pedal then it sounds like air has got into the brake system depending on how you did the bearing job

Bang on Decks and thats why you should not attempt these kind of jobs unless you know exactly what you are doing ..to late after and it will cost you all the more now with the car having to be off the road and done correctly by a qualified engineer ..

@ PNL
It's easy to slag people down when things don't go the right way.
Replacing the bearings is a straightforward job, maybe I got unlucky with my ABS.

@ Morty Mort
The magnet ring attached to the bearing is fitted to the inside off the axle so the ABS sensor would detect it.

@ Deckchair5
Thank you for your explanation it's clear to me now.


Greetings
Frank

lammy1 said:

@ PNL
It's easy to slag people down when things don't go the right way.
Replacing the bearings is a straightforward job, maybe I got unlucky with my ABS.

@ Morty Mort
The magnet ring attached to the bearing is fitted to the inside off the axle so the ABS sensor would detect it.

@ Deckchair5
Thank you for your explanation it's clear to me now.


Greetings
Frank

Click to expand...

Not slagging you down at all [I have changed many bearings myself] just pointing out that somes time leaving things to the pro 's is the best option

@ PNL

Sorry that I took it wrong.......
Frank

Here's a picture (not a Stilo though) of an ABS magnetic ring or "tone" ring along with the ABS sensor mag pick up

The ring needs to be clean of metallic particles and the sensor needs to be at the right air gap, close enough but not touching, to pick up the magnetic field variations

See if you can buy a Stilo Maintenance manual from Ebay, they're under £5 and will save you a 100 times that

Decks the graph you have posted is not a digital sensor pattern, the Stilo has digital sensors which give a square wave pattern and have a power supply directly to them from the ecu. Common problems during wheel bearing fitment are:-

fitting a bearing round the wrong way, the brown plasticky looking ring is the ABS ring and this must face to the centre of the car.

damaged wheel bearing ring, normally due to poor fitment.

damaged speed sensor, these are normally very tight and can be broken if not treated carefully.

the retaining circlip fitted so the gap is NOT in line with the sensor hole so the circlip blocks the sensor from reading the ring.

Copper slip type lubes used, no metalic based lubes near magnets guys.

Rust or swarf stuck to the magnetic ring causing a magnetic short.



If the warning light comes on and stays on then it would tend to be a sensor problem given the repair already done as the system has detected a fault on its pre start up check (probably an open circuit in a sensor).

If the warning light comes on, goes off and then only comes back on after the vehicle is moving, this means the pre start up check was all ok and the fault is due to a speed signal not being present or faulty, (usually a bearing).

Hope this helps. By the way fluid level should bring on the low level warning light and then the abs light.

And that guy is the professional ..nice post NumanR

Nice to be back Phil.

Decks posts alot more than me and 99.999% of the time is correct. Everything he said still applies. Good luck finding the fault.

Hey now, hold up, I didn't say that was a Stilo waveform, that's just one from the Picotech waveform library (as it says on the label)

That isn't a Stilo wheel bearing either

Thanks for the clarification though

Nice to have you back NumanR

Nice to have a few minutes to come back and see whats happening.

I still have problems with my ABS.
Went to the garage and they reseted the error, but after 1 km the ABS warning light came on again.
When they connected the computer again they saw that the two rearwheel sensors didn't got any signal.
OK to break one sensor is stupid but two?????

The strange thing also is the dustcap from the old bearing didn't fit the new ones.
I told this at the garage and they also wondered how this could be.
Going next week again to the garage and look further.
The story continues.

ps. can some body tell me how far the ABS sensors should be from the magnetic ring on the bearing?

Frank

The sensor should be as close as possible without touching the ring. Usually a very thin spacer is used to set it up if it's adjustable

Can you do some electrical tests on the sensors?


SENSOR CIRCUIT CHECK
Ignition off- Set multimeter to resistance - check the sensor for continuity ie not a open/broken circuit
Disconnect the sensor connector and check the resistance across the two pins of the sensor.
No resistance = short circuit.
Infinitely high resistance = open circuit
Small resistance is good


ECU VOLTAGE INPUT
With ignition on check for voltage at one of the pins in the other connector coming from the car abs
No volts means no input is coming from ABS control unit and means the problem is upstream from the connector
If you have a voltage then the problem is at the sensor or in the return swignal line

SENSOR OUTPUT SIGNAL
With ign on check for a fluctuating voltage at the other pin -the return signal line when you rotate the wheel
Fluctuating voltage is good and shows the sensor is working and picking up the wheel's signal
Nothing happening = the sensor or the tone ring are having problems and not communicating

These bearings really need to be fitted with a hydraulic press to keep the tone ring from damage.

I will do the electronics check this weekend.

How far are the sensors from the magnet? 1 mm, 2mm or?
Now they are about 2-3 mm from the magnetring.

I also couldn't find any adjustment off fittment off the sensors, ie I couldn't get them nearer or further from the magnet.
There only is a hole and that's it.

Frank