Note On INTERMITTENTS:
WARNING: This page is about a different car, the 1986 Oldsmobile Toronado and 1986 Buick Riviera. However, it is still accessible from the selected car via links, so may be relevant.
If an intermittent Code B124 is being set, manipulate the related wiring while observing BCM data parameter BD60. If the failure is induced, the reading will jump from a normal value to 0 MPH.