Abs light, shuddering brake pedal

[larm22]

2010 Aygo  has developed a shuddering brake pedal issue. Starts when  braking from anything over 30mph, shuddering in pedal and car pulls to the right slightly as if has locked up. This can happen for around 10/15mins of driving then ABS & handbrake light will come on. Once these are on issue stops and I'm able to brake at any speed with issue, other then lights being on. Car has had new wheel bearings in either side and new brake pads/discs. ABS sensor has been changed on right side but issue still ongoing

[flash22]

Any drop in brake fluid level, and codes been stored ?

[Vandals01]

Any of the following will have cause this:

• Faulty Speed sensor in any one of the 4 wheels
• Front Bearing fitting in the wrong orientation (one side of the of bearing had a magnetic tone, if the garage fitting on tone ring on the outside as opposed to inside, it will not give magnetic signal to the speed sensor).
• Faulty ABS module

Anyway, you'll need GOOD diagnostic tool to pin point the problem.  Get an OBD2 reader that can give you LIVE data, allowing you to read the wheel speed in all 4 wheels.  jack the car up one wheel at a time, then just spin the wheels by hand.  If any of the wheel is not picking up speed signal, then you know which wheel to investigate.

 

Update: Consider the cost of a good diagnostic tool, you might want to pay a garage instead.  But is the garage competent enough to handle this issue will be the true dilemma.

[larm22]

No drop in brake fluid. No codes stored but this was using a reader that's not great. If the wheel bearing was fitted the wrong way, would this cause an issue straight away? As passenger side bearing fitted about 2 months ago and drivers after the issue with braking started?

[Mjolinor]

If your ABS light is on then it will have codes stored.

Get a laptop and buy a Delphi reader for about £40 from China.

If the bearing was the wrong way round then a fault would be immediate so if it has been OK I would suspect a sensor has gone faulty or is not quite mounted correctly.

[Vandals01]

3 hours ago, larm22 said:

If the wheel bearing was fitted the wrong way, would this cause an issue straight away?

Yes.  If the bearing was fitted in the wrong orientation, it would happens almost immediately.

Hang on!

Does the shuttering happens at all speed or only above 30 mph?

[flash22]

basic scan tools will not read the ABS

you can perform the paper clip test by linking 2 pins turn the ignition on and count the flashes of the ABS light, it should give you a 2 digit code, if it continually flashes no codes are stored

 

Edit, I bet it's a cheap Chinese aftermarket abs sensor, because it's new doesn't mean it's good

[larm22]

Shuddering happens once I'm travelling over 30mph then breaking. Took it to a garage who said no stored codes?! They said it could possibly be the abs pump. 

[Vandals01]

He could be right, because the ABS module (the electronic proportion) is in the ABS pump.

But what happens if you changed the ABS pump and problem still persisted?  4 new speed sensors?  Then 4 new wheel bearings?

What is why I stress the importance of diagnoise it propperly, not just throwing parts at it (Parts Cannon Approach).

At the bare minimum, find out what is the reported speed at each wheels when the ABS became active (i.e. during 30mph+ braking).

[flash22]

Do the above test and see if it brings back anything

do you have matching tires on the front if so how old are they (it's marked on the side wall) are your tire pressures correct, has the car ever had the alignment checked

[larm22]

19 hours ago, flash22 said:

Do the above test and see if it brings back anything

do you have matching tires on the front if so how old are they (it's marked on the side wall) are your tire pressures correct, has the car ever had the alignment checked

Matching but I do need to replace as one is mishapen ( was an advisory in MOT ). Car had alignment at beginning of the year after first wheel bearing was changed. Will carry out test, replace front tyres and take it from there

[larm22]

21 hours ago, Vandals01 said:

He could be right, because the ABS module (the electronic proportion) is in the ABS pump.

But what happens if you changed the ABS pump and problem still persisted?  4 new speed sensors?  Then 4 new wheel bearings?

What is why I stress the importance of diagnoise it propperly, not just throwing parts at it (Parts Cannon Approach).

At the bare minimum, find out what is the reported speed at each wheels when the ABS became active (i.e. during 30mph+ braking).

That's my worry. Spending more on something that may not fix the fault

[flash22]

Misshaped as in square off or scrubbed, yes that can cause an ABS issue

[fossyant]

Also consider a broken ABS sensor ring. Any crack in these will throw the ABS light on at speed. Happened to another car of mine. Would only trigger at 50 or above.

[flash22]

1 hour ago, fossyant said:

Also consider a broken ABS sensor ring. Any crack in these will throw the ABS light on at speed. Happened to another car of mine. Would only trigger at 50 or above.

Its part of the bearing

only other thing that springs to mind is the caliper is hanging up and slowing 1 wheel quicker that the rest