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Robert
Robert, UK Qualified Car Technician
Category: Car
Satisfied Customers: 5390
Experience:  Fully qualified / self employed garage technician in the UK
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I have had my driver's side sensor replaced, because my ABS

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I have had my driver's side sensor replaced, because my ABS light came on intermittently. The computer said that had fixed it no problems. The light still comes on intermittently. When I put my foot on the brakes, sometimes I can feel a grinding sound which frightens me. Any ideas?
JA: Is it just the ABS light? Or is the brake system warning light on, too?
Customer: Just the ABS light.
JA: What is the make/model/year of your car?
Customer: Hyundai Matrix 2008
JA: Are you fixing your Matrix yourself? What have you tried so far?
Customer: No. I had the sensor fixed Thursday at a garage.
JA: Anything else you want the Mechanic to know before I connect you?
Customer: Is it dangerous?
Customer: replied 4 days ago.
I checked the brake linings they are low but ok. The brake pedal seems soft, goes down more than usual
Customer: replied 4 days ago.
It only happens when you put your foot on the brake pedal. It feels like something metal to metal. Hard to describe.

Hi..there..

The grinding sound with ABS light could be the abs activating.. I note you mention they replaced the sensor, but they also need to carefully inspect the tone ring that the abs sensor actually senses..that normally on the driveshaft outer cv..any small crack or missing tooth on that ring could flag up an ABS sensor code... Although the ABS assists with hard braking its not at all dangerous to drive the car...but it not something that should be ignored as itnow a instant fail on MOT.... but if you brake pads are low or nearing the metal backing with very little braking material left - both inner and outer pad.then they should actually be replaced.. Any other questions?

Customer: replied 4 days ago.
Would a good mechanic pick up on this time ring. If it's not that what could it be?
Customer: replied 4 days ago.
Tone ring

Its called a "tone ring" this what the abs sensor needs to see for it to send a signal back to the abs control module..

Well ABS faults arent that all uncommon, most good mechanics with the proper diagnostic tools,scope's ,and visually checking the tone ring can diagnose and sort this....

Unless you have a decent scan tool to plug it in as the fault occurs, then thats the only way we will know what kind of problem is occuring here?

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Customer: replied 4 days ago.
If the tone ring needs replacing, will this stop the funny grinding knocking noise.

It should do.. but if i was to advise..get it properly diagnosed first and take it from there...these systems arent that hard to diagnose..so any decent mechanic with proper equipment should be able to reach a solution and a fix quite easily..