abs comes on at stop

dealer2 · 03-29-2008, 02:40 PM

I have a 96 g cherokee with 4x4 auto v8.whenyou are almost stopped the abs applies.There are no codes in system.If I drive with scanner hooked up it operates fine.I bled brakes and fluid looks good .I have no history on veh ,my customer bought it used and the problem was already there.Any ideas?

speedbullet2 · 03-29-2008, 02:52 PM

You bled the abs system with a drb tool? if not id try that first may have air bubbles in it i had a similar problem in another vehicle was the abs unit had air in it that normal bleeding wouldn't remove.

indept · 03-29-2008, 03:26 PM

Are you sure it's ABS & not just warped rotors causing the pedal to pulsate?

speedbullet2 · 03-29-2008, 03:35 PM

Ive never had the rotors cause a pulsating condition but i suppose it might be possible im no brake expert by any means but thats where i would start is with the drb tool and bleed the abs unit.

indept · 03-29-2008, 04:14 PM

Warped rotors WILL cause pedal pulsation

**tsconver** · 03-29-2008, 04:17 PM

Quote:

Originally Posted by speedbullet2

Ive never had the rotors cause a pulsating condition but i suppose it might be possible im no brake expert by any means but thats where i would start is with the drb tool and bleed the abs unit.

you work on brakes often??? brake pulsation is almost always warped rotors or run out issues, usually a lower frequency pulsation that is speed sensitive. The ABS pedal pulsation feels nothing like a warped rotor. It is a much faster higher frequency pulsation and is not speed sensitive.

**Texas ZJ1** · 03-30-2008, 12:45 AM

Gents,

it could also be a bad ABS computer.

Hunter

**Texas ZJ1** · 03-30-2008, 12:46 AM

A simple way to check that would be to unplug the ABS system and see if the brakes still pulse during deceleration.

Hunter

ninethreezj · 03-30-2008, 01:08 AM

If I may add to what Hunter is saying, I would say that it is a great idea to check the braking system by disabling the ABS system. I unplugged the relay for the exact same issue that you are having (User - Kyle suggested this), and now I have brakes again.

My issue may have been different from yours: as I was rolling at any speed then apply the brakes, all is well until I am at about 10-5 mph; this is when the ABS system makes a loud noise, makes stopping significantly more difficult, then stops really hard. Ultimately, it seemed as though I was stopping on a really slick surface and get that audible ABS sound, then total lock-up.

I have since not plugged it back in; I would not suggest leaving it out forever, as you run the risk of locking up really easily.

Hope this helps.

speedbullet2 · 03-30-2008, 01:16 AM

Quote:

Originally Posted by tsconver

you work on brakes often??? brake pulsation is almost always warped rotors or run out issues, usually a lower frequency pulsation that is speed sensitive. The ABS pedal pulsation feels nothing like a warped rotor. It is a much faster higher frequency pulsation and is not speed sensitive.

Nah i dont work on brakes and i thought he said it was abs pulsation thats why i recommended the abs unit drb tool bleed anyways good luck on fixing it hope we were of some assistance.

EDIT: On my post about pulsating rotors IMHO i call that a wobble thats why i confused people in saying i never seen rotors pulsating.

**AgitatedPancake** · 03-30-2008, 02:32 AM

Quote:

Originally Posted by speedbullet2

Nah i dont work on brakes and i thought he said it was abs pulsation thats why i recommended the abs unit drb tool bleed anyways good luck on fixing it hope we were of some assistance.

EDIT: On my post about pulsating rotors IMHO i call that a wobble thats why i confused people in saying i never seen rotors pulsating.

the rotor has a wobble which causes a pulse in the brake pedal, but ABS is VERY fast, happening probably near 10 times a second.

madrabbitt · 03-30-2008, 02:43 AM

abs pulse feels like a vibration then a pulse.

warped rotor feels like a shake

Kruzin · 03-30-2008, 03:00 AM

It could be a sticking cylinder in one of the calipers/drum cylinders. I have had a sticky caliper that would cause the ABS to trigger. A short drive on a dirt road made it easy to figure out which wheel was sticking...

It could also be a bad ring tone sensor.

speedbullet2 · 03-30-2008, 03:04 AM

Quote:

Originally Posted by madrabbitt

abs pulse feels like a vibration then a pulse.

warped rotor feels like a shake

Ill x2 on this but everyone has their own opinion lets just all have some

and call it a day

**tsconver** · 03-30-2008, 09:09 AM

Quote:

Originally Posted by speedbullet2

Nah i dont work on brakes and i thought he said it was abs pulsation thats why i recommended the abs unit drb tool bleed anyways good luck on fixing it hope we were of some assistance.

EDIT: On my post about pulsating rotors IMHO i call that a wobble thats why i confused people in saying i never seen rotors pulsating.

makes sense then, abs defintiely feels different than warped rotors as someone mentioned warped rotors can also be felt in the steering wheel as a wooble back and forth, abs usually does not cause a huge steering wheel pulse.