The hall sensor used on the smallcar sensor is pole sensitive - I found
mine was only "sensing" one out of five magnets because the others were
installed backward.  Once the vss is installed, test by hooking the red
wire to power, the black to ground, and the green to your volt meter.
I believe meter should read 5 or so volts when sensor is not over a
magnet and drop to zero as it passes over a magnet.  Or maybe vice
versa?  Spin the wheel and make sure it's reading every magnet.  If
not, try popping the magnets out and gluing them back in with alternate
polarity.  Hope that helps

Kevin Jakey 
9:37 AM 1/10/2007