ABS triggered, new to me.

[lsmalley]

Having issues with my abs being triggered when going over bumpy roads. I don't recall this ever happening unless I was driving in snow or loose gravel. So, I know this would indicate that the abs is functioning as the light goes right out, but what could be causing this? Also, I only notice it when the front passenger tire goes over bumpy roads. Last night I cleaned the wheel sensor and hub and still no change. Running new Bilstein HD, tie rods, steering damper, idler bushing all functioning properly. Did the tie rods and struts a few days ago and problem existed before then. Control arms and ball joints are also fairly new (Lemfoerder). Any suggestions?

[porkface]

done lots of front abs sensors on 124s and 201s for that very reason. drive it on smooth pavement at 5-10mph and put your foot on the brakes. if the sensors need replacement, the abs will make the pedal dance. good luck, chuck.

[Rrrockhound]

I had similar issues with the ABS on my '87 BMW and my Silverado. If cleaning the sensor and hub didn't fix it make sure the reluctor (toothed ring) isn't broken. You may have to put a voltmeter on the sensor and spin the wheel by hand to confirm which sensor is the bad one. I'm not sure what the voltage should be for your car, you'll have to look that up. In the case of the Chevy, even a slight build up of rust on the sensor mounting point is enough to increase the gap between the sensor and the reluctor and cause issues. In the case of the BMW, new sensors were cheap enough that I found it was easier to just replace them than try to diagnose them.