The same way it does on any car - wheel speed sensors. >Just how does ABS determine a wheel is not getting grips in AWD system? -- ----------------------- Grant Lenahan gfl at erols.com (home) glenahan at telcordia.com (office) NEW! gfl at alum.MIT.edu (MIT) (973) 377-4458 voice (973) 377-3661 fax (973) 301-0685 Sonogy Lab