Hi all, after a disc and pad change I have noticed the abs cutting in sometime on slow hard breaking. It only cuts in just as the car is about to stop - like when you break hard on snow. Only does it for a second. Would this be faulty/dirty sensor. Breaking from high speed is fine - just does it for the last second before the car stops when it is going slow.

To be honest it may have done it before but because the new brakes are so much better I use them harder then the previous discs/pads.

Thanks in advance for any advice before I take the wheel off and check the sensors, remove discs and check tone rings or whatever the correct word is.

 

Probably newness ABS self checks itself twice first when you turn the ignition on and then all the time when in motion. So in theory no light no fault.

 

Are we guessing the car?
I find my newage sti does this a fair bit, especially if there is anything that could cause a slight skid, gravel/snow, only on hard stops,
But never had this on my classic, I know that sti`s have G sensor so I wasnt sure if it was anything to do with this extra element.

 

Well if there is snow, gravel etc it's doing exactly as it should. What car it is doesn't really matter. Could be any make too. G sensors have an effect on a lot of VAG cars but have never come across any problems with a Subaru YET.

 

Sorry - my mistake. 2003 Impreza Sti. My car will do this also in the dry. Could it be the tone ring or dirty sensor? I have no fault lights on.
Adrian

 

anything wrong with abs sensors or tone ring it should throw a code

 

I'd go with this. With all the cars I've driven and worked on, the only sole exception was a Megane 2 with a damaged rear reluctor and that triggered the ABS when lightly braking with a tiny bit of steering input, any other time it was fine and it took a few thousand miles before it eventually threw a code.

Most of time a sensor or reluctor issue results in ABS activation during every braking event regardless of how hard the brakes are used, or on cars with ESP it triggers on acceleration (classic case is BMW E6x/E90 rear reluctor rings fracturing that prevents acceleration)

When I've experienced unexpected ABS activation at any other time it's boiled down to either a physical brake issue, tyre problem or suspension/damping problem.

Being a GC8, I'd be tempted to pull the fuse and do a few slow emergency stops and see which wheel grabs first. You should expect to find both fronts locking first, but if rears grab first or the same front wheel always grabs then there's an underlying mechanical issue.

I've had issues on my old GC8 where front discs had glazed causing both the rears to grab first during the first three or four 30mph emergency stops. That created very scary unexpected ABS interaction changed front pad brands fixed that. Recently our Zafira pool car started doing this and it turned out a rear tyre had structurally deformed.

 

Thank you so much for the information.

 

Nothing You could understand,worthless for You Zany