So, I've been without ABS/TC for a while, finally reset everything last night and then coming to a slow stop the ABS kicked in, three lights came on but no fault code was stored and restart brought everything back.

This morning curious about things I pulled the rear pads, and they're down to almost nothing. These were new OEM pads less than 2 months and 3000km ago.

Ideas? The front pads looked OK last time I checked them.

 

It sounds like you are not running on your front brakes, I would suggest you get some rear pads installed and as soon as the ABS lights up again get the codes read

 

OK, I had guessed it was seized rears but they seem ok. Would a small amount of air in one of the fronts potentially cause something like this?

 

You'd have a reall soft pedal if not one that nearly goes to the floor if it were a front air in the lines problem.

 

Hrm, could EBD have been set to a severe rear bias prior to the rear sensor failure and left the system balanced for that condition right up until the code was reset?

 

Some more information. The premature ABS kick-in at low speed is caused by vibration in the caliper. I'm starting to think that brake dust is irrelevant to the three amigos, looking at the mechanics of things there just isn't any way that could be interfering. What does make sense though, and I've seen this a couple times (when the detroit was misbehaving for example) is that worn pads squealing cause vibrations which causes the reluctor ring to move supersonicly which would generate excessive voltage at the sensor coil. So the issue is really bad software without allowances for ignoring that kind of spurious signal.

Of course this means that without the software in the SLABS module I don't think there is anything that can be done to fix it. There are a few NVRAM settings in there that are undocumented and I'll contact Wabco and see about what could possibly be done. A proper fix will cure the problem once and for all.

 

Oh one more piece of information, the problem gets worse when the hub bearings are worn, so not being able to rebuild and tighten the bearings in D2 hubs means that once it starts happening it becomes a hair trigger and will happen again and again due to the extra play amplifying the screech into movement.