Jezziebx16v wrote:
As far as i know if the ABS light is on you aint got no ABS full stop, if only things were as easy as you suggest.
Jez
hi there,
my abs light is on and the abs system does work, as in when i drive along and hammer the brakes it may skid on one wheel for a sec but it dont keep skidding. that means the abs works because the skid dont continue. the light is solely on because there is a faulty sensor or a sensor that isnt giving proper or accurate readings.
The pedal should hammer under your foot when the brakes are applied hard. By hammer, I mean pulsate quite quickly.
If it's locking up and then not skidding, I'd suggest you have brake fade not ABS.
Best test if it can be done, is to take the car onto a grassy area, get it up to about 15 - 20 mph and stand on the brake pedal; it will audibly rattle as the ABS kicks in. Under 10MPH, the ABS doesn't work.
All it takes is one sensor to be out of action and that renders the entire ABS system inoperative, otherwise you'd have one wheel locking and the others just not operating trying to compensate for the locked up one and the car would pull violently in the direction of the locked up wheel.
hi there,
well that may be in theory but that is not whats happening in practice. my abs light is on and the abs works. next time im at my garage i will drive the car down the road and hit the brakes hard as poss and you will hear no skid prolly cos it dont always skid. you will know because i will video it and slap it up on the forum.
As I say, that doesn't necessarily mean your ABS is working but more likely your brakes are crap.
If that pedal doesn't pulsate and if you get any lock up at all, that you reckon you are getting on initial braking, the ABS is definitely not working. My guess would be partially seized calipers. If you've got a warning light on telling you that the ABS isn't working and it is, best get that in the Guinness book of records.
I'd suggest you get it checked out real quick if you drive it much before you find you're living in denial and wrap yourself around a tree or run over someone.
Alan S
Last edited by AlanS on Thu Nov 16, 2006 12:26 am, edited 1 time in total.
AlanS wrote:As I say, that doesn't necessarily mean your ABS is working but more likely your brakes are crap.
If that pedal doesn't pulsate and if you get any lock up at all, that you reckon you are getting on initial braking, the ABS is definitely not working. My guess would be partially seized calipers. If you've got a warning light on telling you that the ABS is working and it is, best get that in the Guinness book of records.
I'd suggest you get it checked out real quick if you drive it much before you find you're living in denial and wrap yourself around a tree or run over someone.
Alan S
hi ..well thats like pure cheek!
a) my abs light is on
b) my disks and pads are new
c) the wheel doesnt always lock (which indicates a sensor that works when it wants to i.e faulty connection)
d) my abs does work. as obviously if you slam the brakes on and it does skid for a moment but not permanently the abs has sensed the lock and unlocked it. man thats how it works!!
If that's what you reckon, well good luck mate, you're going to need all you can get.
If it just simply doesn't lock the wheels and it doesn't pulsate underfoot, it's a case of the brakes not working more than the ABS does. If a wheel locks even for one second, the ABS is inoperative.
I was involved in various levels of motorsport for a long time and even to this day, I get the chance to give opinions on high performance cars as one of my sons has a business that tunes everything from road cars to racers and drag racers and whilst I'm not going to argue with you about it, if I was to give an opinion on a car for competition that does what you reckon yours does, I'd take the wheels off before someone killed themselves in it, that's how potentially dangerous I reckon it is. You've got to be living in denial trying to convince yourself otherwise but as I say, I'll withdraw from the issue at this point, but when you wrap it up against something, I'll have a clear concience that I did all I could to warn you.
Out of curiosity, how did you bed the new pads and rotors in? The problem may even lie there if they're glazed.
thanuttiscotsman wrote:hi there,
would it not be even easier to just drive down the road and hammer the brakes on then whichever tyre skids has the dodgy sensor?? as mine has a dodgy one i assume as my lights on but when i drive it in the car park and hit the brakes it sometimes skids but only the front right wheel iirc.?
cheers rossco
As far as i know if the ABS light is on you aint got no ABS full stop, if only things were as easy as you suggest.
The ABS computer is in reality two computers working in tandem. They both do the same task and compare the results. If they dont tally with each other, a fault is logged and the malfunction light illuminates.
At power-up time, the computer sends a current to all four sensors, and any low/zero readings from open circuits or short/high resistances, will cause the lamp to light. (or even low battery power)
When the car is in motion, (5MPH, upwards) the computer looks for a sine wave type signal from each sensor (the driveshaft teeth interrupting the magnetic field creates an alternating current, like a mini alternator). The frequency of the current tells the computer the speed of each wheel, which obviously should be about the same, taking into account cornering and slight wheel size differences due to tyre wear etc (or the lamp lights!).
SO, as you can see its a sophisticated system. The bottom line being: The lamp may be lit, but DEPENDING on the nature and type of fault, and whether it is permanent, or otherwise, an ABS system can STILL provide an anti-locking function. It needs to be able to do this, so that if a fault occured whilst the ABS was doing its job, the wheels woul not suddenly lock and perhaps cause an accident. Incidently, a non-working ABS should still give the same braking efficiency as before(according to Bosch/Teves)
but experience suggests a slight reduction in effectiveness.........
hi there,
well it seems a few people have different opinions here. but from what i can see if abs dont work the car skids simple! and not just one wheel for one second etc. also i never said if my pedal does or does not pulsate so where that came from i dont know. and i dont use my car i never have! as it says in my signature its been in my garage keeping warm n dry since i got it. also it was a citro guy who replaced the brakes before i got the car, they were already fitted. ive never had the pads out the car. of course when i first drove it in the field the brakes were pretty poor but that was a rust issue on the disks. but after a bit of going and stopping they were fine and the car doesnt pull to one side under heavy braking. now the info i have posted up about my car is completely true! thats what my car does whether other people like it or not and im happy to post up videos with my fuses in out or glued to the roof because you will see IAM NO LIAR. i dont live in denial i live in an apartment. if my cars abs didnt work then id happily say that as what difference would it really make to the price of cheese. none! may sound sound incorrect to the technical side of how its supposed to work but these cars are very good at defying that.
On the Citroen BX 16v, if the ABS light on = fault in the ABS system. For safety reasons the entire system is then disabled until the fault is rectified - because ABS going haywire is potentially worse than no ABS at all!
If that's not true then I'll gladly down a pint of LHM.
If your ABS light is on but you still have functioning ABS, then the fault may lie in the circuit to the ABS lamp, causing it to light in error?
RobC wrote:If your ABS light is on but you still have functioning ABS, then the fault may lie in the circuit to the ABS lamp, causing it to light in error?
hi there,
well rob that does certainly make alot more sense to me than being told what i have seen with my eyes is not true. one question i have is if the brake pad low warning wire is not connected does this cause the abs light to come on?? as i know that one of the wires at the front is snapped off but dont remember which side. my car was completely riddled with wiring probs when i got it because mice were living under the back seats and they ate alot of stuff including the gearstick head seats etc. but thankfully i have solved most of these problems now including changing the interior and cleaning out all the car etc. i have repaired alot of wires in there. now mostly everything works but the brake lights dont and the abs light is on, apart from that she is pretty happy.
i don't know about other peoples BXs, but on mine a good way to tell whether or not the ABS circuit was on or not (even if the light wasn't working) was this:
1. switch on ignition (but don't start engine)
2. listen
3. roughly the same time that the oil level needle wakes up (about a second after turning on the ignition) there is the distinct sound of a relay clicking from under the left side of the dashboard. if this relay clicks, it means the ABS circuit is ON, and the ABS lamp on the dash extinguishes at the same time.
hi there,
rob when i turn my ign on there is an almost instant relay click actually sounds almost like 2 simultaniously then another 1 click about 2 seconds after that. it does this everytime i turn the ign on.
