ABS problems



  • My ABS keeps kicking in when I brake gently to a stop. However if I brake hard and stop quickly it doesn't kick in.

    It used to do it all the time, I though it was because one of my rear calipers was goosed, that got replaced as well as the other side and s/s lines put on.

    What could it be?

    It started happening after I had an ABS sensor changed, it was reading from the goosed caliper. The mechanic hooked it up to the computer and it read that it was a faulty sensor. the caliper was fooked too though, the outside pad kept wearing out while the inside pad didn't even touch the disc.

    help me please it so annoying!



  • Hi James,

    This is normally a sign of a split ABS ring, the toothed ring on the front CV's and the rear hubs.

    When the rings splits the gap between the theet on the offending split get slightly bigger and the sensor thinks the wheel has locked so kicks the ABS in.



  • Wise words Mikey. I take it the toothed ring is least clean?



  • is it just a case of checking each one? or is there and easy way, the fronts are pretty easy to see but the rears need the disc removing don't they!



  • @7f4985cf04=jamesmx3:

    is it just a case of checking each one? or is there and easy way, the fronts are pretty easy to see but the rears need the disc removing don't they!

    Yea it is a case of just looking at them and checking for damage. First place to start looking would be the brake that has just had work done on it.

    Rear disks are easy to take off though. One bolt holding the calliper on, undo the bottom bolt and you can swing the calliper up and then withdraw it off the top slide bolt. Then 2 more bolts holding the pad and caliper carrier in place. 2 more small retaining screws holding the disk to the hub. Give the disk a whack with a hammer on the centre (not on the surface the pads grip) and it should just come off.

    If you want to properly check the ring you'll have to remove the hub. Remove the dust cover in the centre with a hammer & screw driver. Then get a 32mm socket and undo the centre nut, the hub will then withdraw and you can clearly inspect the ABS ring.



  • you need a BIG breaker bar to get the 32MM nut off though

    maybe give the abs rings abit of a clean before going to all that effort first though



  • I'll wait 'tll i do my discs then which should be soon! If they turn up.

    Are the rear rings the same as the front, i have a CV in the garage with a good ring on it, wondering if it'll fit?



  • checked all the rings yesterday, when i did my new discs and pads, they all are fine, no missing teeth and no cracks either. I cleaned them with brake wash too just incase they were dirty and that was the problem, but they didnt really need to be cleaned.

    It still cuts in when i slow, but the abs light doesnt come on when it kicks in, it does light up on start up though like its meant to so the bulbs not gone.

    any more ideas guys?

    I was wondering about the abs ecu thing thats under the passenger seat, could that be broken and cause the problem?



  • I'd start looking into the wiring side then?

    have any wires been worn on the abs sensor? etc

    unsure if the black box could be the problem…don't see why it couldn't? i'd check for worn abs wires first though, where is moves with the steering/suspension



  • Head scrather James :?

    Was kinda hoping it was the rings as it's easier to sort rather than going through all the wiring.

    Have you tried Marco's ABR codes pull? Might shed some light on it.

    Can't see it being wiring to the sensors as this 'should' trip the light on the dash to come on as it thinks a sensor has stopped working. Still worth a look though.

    Worth looking at the abs ecu under the seat. Check all the wiring is intact. With the passenger seat moving something might give after all these years. The newest MX's out there are pushing 11 years old now.

    Strange this as when the ABS cuts in early is normally due to the system thinking a wheel as locked. Might even just be a duff sensor not reading properly. As to which one though could prove tricky to find if no fault codes are stored in the ECU.



  • thanks for the replies, Nothing stood out on the wiring side under the car (in the arches) on saturday.

    worth pulling the front seat, and checking the plugs are in properly or any faulty cables?

    I had thought that the new sensor might not be in the right position, maybe too far away from the ring? I'm not to sure how they work, as i understand, the sensor picks up either the gaps or the teeth, and senses if theres too long a time without a change. this idea is flawed though as surely it would do it all the time?

    I cant work out how to pull the codes, I'm not sure if its OBDII as its 1998, but I cant find a plug inside the car.



  • driving home tonight, the ABS light popped on for a second then went out, i was coming to a gentle stop, and the pedal wasn't doing its usual chatter. The light went out then as i slowed to a stopped i got the chatter back but no light.

    It also flashed on when i was cruising along at 40ish.

    any more ideas, also how can i check if the ABS ECU is fine?



  • ^^ lights coming on, was loose -ve on the battery

    took it in to mazda today, they said:

    All ABS rings are in good order…

    When the old ABS sensor that was removed, the bolt broke, instead of drilling and tapping it, the mechanic just welded the sensor in place, but its in the wrong place. the tolerance for the 'sensor to ring' gap is between 0.3mm and 1.1mm but mine is further away, therefore when the sensor trys to read the spinning ring, it cant see it and thinks the wheel is locked.



  • @fcb75be99c=jamesmx3:

    ^^ lights coming on, was loose -ve on the battery

    took it in to mazda today, they said:

    All ABS rings are in good order…

    When the old ABS sensor that was removed, the bolt broke, instead of drilling and tapping it, the mechanic just welded the sensor in place, but its in the wrong place. the tolerance for the 'sensor to ring' gap is between 0.3mm and 1.1mm but mine is further away, therefore when the sensor trys to read the spinning ring, it cant see it and thinks the wheel is locked.

    Result! Glad you found the problem mate.

    That's why I origianly though the ABS ring was cracked as you get the same symptoms as the sensor can't read the ring properly.

    I guess you have the head ache of sorting it out now.



  • yeh, went into the garage who did the work, it was last november though, he remembered and is going to look at it next friday. No metion of cost though, it should be free since I already paid for it!


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