Quote:
Originally Posted by BackintheFold
My brakes are clearly playing up.
Everything is fine if I switch the ABS system off.
With it on, as soon as I brake (when moving) I get a weird valve-fluttering noise from the brake area (ABS unit and/or the" bomb")
It keeps making a noise like its trying to pressurise or a relay is fluttering until I switch the ABS off.
Any ideas? Is it likely to be the sensor gaps needing adjustment, or the sensor "ring" needing cleaning somehow.
Is it possible to check the sensors somehow? I don't have an oscilloscope so it would be by measuring voltage or resistance while spinning each wheel
Off the ground...
Thanks in advance for any/all pointers.
|
It sounds like an issue I experienced with mine. Turned out to be the front o/s sensor out of adjustment. I assume after the fluttering, you get the ABS light on the dash?
Firstly, check you have continuity by unplugging the sensors at the strut tops/either side of the fuel tank in the boot and testing across the 2 pins.
If that's ok, it's likely the sensors are out of adjustment. If not, and like mine recently, the cable is probably toast, crumbling and corrosion is to be expected.
I tried trial and error adjustments to no avail, they are incredibly sensitive to changes in distance to the driveshaft ring. I only solved mine with an oscilloscope, I believe the output is around 50 millivolts, not readable with an everyday voltmeter.
It doesn't have to be a specific output, but the 4 corners do need to be more or less the same, it is this difference the system measures as a self-check and throws the system out if it doesn't get 4 readings the same.
Make sure the rings are clean though as well. It won't help if they are clogged.
I now also find I don't need to buy the "disposable" caps for the sensors, I didn't find setting them with these alone to be accurate enough. I do have to revisit the procedure on occasion too. My rear sensor outputs are stable (it's only the fronts that seem to change) so I use these for a reference reading and set the fronts to match.
Sorry it's a bit wordy, but hope it helps.
Geoff