ABS not working

[mnichols]

I was testing my M3 the other day, getting ready for another Sebring event and noticed that I could lock up my front tire on hard braking. The ABS light isn't on, and there are no codes shown on the code reader.

Any ideas what would allow tire lockup without any ABS symptoms?

[Manolito]

I presume that you verified that the ABS bulb illuminates when you turn the key to the On position (i.e. bulb not burned out). I would try swapping out the fuse, even if the fuse looks good.

Do you feel and hear the growl as the the system self-tests when the car hits (I think it's) 8 mph forward after each restart?

Your post says "front tire" (singular). Are the brakes actuating evenly or is it favoring one side?

If the ABS has failed, you can probably find one at a junk yard. Failing that, we found a guy in LA who rebuilds ABS electronics. He did the ABS from one of our Volvos for a fraction of the cost of a new one and it is still working fine three years later. I can probably dig up his name if needed.

[mnichols]

Thanks for the ideas. I did reference only the right front locking up, but that only happens in extreme braking situations. I have slighty more weight (40lbs) on the left front tire than the right. When I reach that magic 99.9% braking point the right lets go slightly before the left.

The ABS light does work when the ignition is first switched on, so I suspect something else. Don't know if the ABS light would work if the fuse is blown, but I will check that anyway it seems like a good idea.

[mnichols]

I've checked all fuses as suggested, but all are ok. Does anyone know if either of the ABS relays have failed if error codes are created?

Since my reader does not show any codes, other than shotgun replacement, I was wondering if there were any other troubleshooting ideas.