crazy abs malfunction

[EuRoSp1c]

so my abs has been acting up for a while, i always feel it kicking up for no apparent reason. so today im driving down a normally busy street.. i go into boost and feel the car slow down.. and then boom abd slams in and stops my car to a screeching hault as if i had slammed on the breaks. thank god there wasnt a car directly behind me, i wasnt speeding or going around a turn. the wheels just locked up and smoked up the street. does everyone agree that the abs module is definitely shot to hell? funny thing is its a rebuilt one by some company... i almost poopy my leathers :banghead:
is it definately the abs module or can it be something else? any info would help
(THE CAR)

[B518T]

damn dude, I have never heard of anything even similar happening, I would be super sketched out...lol...stay off the freeway...

I would suggest replacing your abs pronto...

I am guessing that you can prolly diconnect the fuse for it and just run without it...

[NK2007]

I don't know if this applies to all b5's but my car won't start without the abs fuse in place.

[burner799]

uhhh I don't think the module has to do with that. usually when it's busted, your ABS doesn't work at all.

Don't our cars use the abs to control wheel spin kind of like a locking differential would? could it be a problem with whatever senses that?

[NK2007]

The abs system uses wheel speed sensors at all 4 wheels. Each sensor sends a signal to the abs control module, which interprets the incoming signals to determine if one wheel is moving at a different speed than the others. The control module then sends the signal to the main abs module/pump to modulate the fluid pressure.

Basically what i am getting at is that the sensors shouldn't be the problem if he is not touching the brake petal. There must be a short or a problem with the control unit/pump. (i'm not sure if our abs computer is separate from the module in the engine bay)

hope this helps!

[akielb]

Your car will run fine with the ABS fuse pulled - pull it - I think it's #7, but check the manual for #. Was it all four wheels? or just one side(did it pull left or right)? Scary stuff! Modulemaster.com FTW.

[ShawFM]

You could have dirty or defective sensors, dirty or defective sensor rings, or a defective ABS unit.
I would pull the fuse until you can get to checking it out or disconnect the harness at the ABS unit. Disconnected the harness on a friends car until his new sensors arrive the car drives fine now. Before the ABS was kicking on and freaked him out how badly it was driving / acting.

[EuRoSp1c]

i tried to pull it but it doesnt start or it turns off when i pull out the fuse. i do have codes for rear speed sensors. could that have anything to do with it? i always feel the brake pad kicking up like the abs is activated.

[EuRoSp1c]

it happened again today but not as bad..... what should i do... any suggestions on what it could be... i dont want this to happen and i end up on the carnage threaddd o_0

[Stumanbmx]

i do have codes for rear speed sensors. could that have anything to do with it?

I believe so

[ShawFM]

i tried to pull it but it doesnt start or it turns off when i pull out the fuse. i do have codes for rear speed sensors. could that have anything to do with it? i always feel the brake pad kicking up like the abs is activated.

Instead of pulling the fuse, pull the harness off of the ABS module. I know my car and friends both ran fine when the harness was disconnected.
ModuleMaster has a video and a picture on how to remove the module.

[Yevmeister]

yeah i got 99 AEB, and run w/o ABS. ABS is for pussies anyway

after coming from 86 GTI, ABS just throws me off


Yev

[EuRoSp1c]

yea im going to disconnect it.... and if i ever come around to fixing it i will.. if not o well..... is there a wat so the abs light and brake light wont come on?

[Toyotatech]

so my abs has been acting up for a while, i always feel it kicking up for no apparent reason. so today im driving down a normally busy street.. i go into boost and feel the car slow down.. and then boom abd slams in and stops my car to a screeching hault as if i had slammed on the breaks. thank god there wasnt a car directly behind me, i wasnt speeding or going around a turn. the wheels just locked up and smoked up the street. does everyone agree that the abs module is definitely shot to hell? funny thing is its a rebuilt one by some company... i almost poopy my leathers :banghead:
is it definately the abs module or can it be something else? any info would help
(THE CAR)

Come screeching to a halt or ABS kicked in? What you described sounds like brake lockup not ABS pulse for no apparent reason.

[EuRoSp1c]

how would the brakes lockup by themselves? thers definately a problem with the abs.. tomorrow im taking day off to do some work on the audi.. so ill disconnect it and see what hapens...

[generik777]

i do have codes for rear speed sensors. could that have anything to do with it?

So fix them. Obviously the first thing you should do to fix your breaks is what your car is telling you is broken.

[Toyotatech]

how would the brakes lockup by themselves? thers definately a problem with the abs.. tomorrow im taking day off to do some work on the audi.. so ill disconnect it and see what hapens...

A bad master cylinder can cause the breaks to lock up. I'm not saying it's not the ABS but complete lockup sounds like another problem.

[B5A4Kevin]

im almost leaning towards the brake pedal switch as abs will only activate (even if overactive) when the brakes are depressed. brake light switches are fairly common on audi's and the new design (i know old a6's use it. it may be the same as a4's) is only like 6 dollars. dirty sensors and damaged rings can cause overactive abs, but so will a loose or faulty/damaged lateral accelleration sensor or yaw sensor. there was a tt i worked on once that had overactive abs. module was ok. speed sensors and rings were ok. fluid level, no faults, everything checked out. eventually found out that the yaw sensor mounted on the steering column was not bolted in place and it would move around while driving and as soon as you press the pedal, abs would kick on. other possible causes are an internally shorted module, or a master cylinder although i haven't seen one fail in this way. if it were my car, i would start with cleaning all the sensors and verifying the signals (block 1 in 03 [brakes]), then replace the brake switch, and go from there. hope this helps.

[EuRoSp1c]

thanx for all the help guys... ill get to work on this and find out the problem

[MacDaddy]

possibly a cracked exciter ring