[s-cars] Intermittent "ABS OFF" light

[Wayne Dohnal]

I'm seeing the orange ABS OFF light come on sometimes, and I finally figured 
out a connection.  Whenever the boost hits 4 to 5 psi the light comes on, 
and it stays there until the boost goes above 6 psi or below 3 psi.  I'm 
suspecting something with the rear diff lock, but I want to check if this is 
a known problem that somebody already knows the answer to.

Wayne Dohnal
1994 S4