The AS SIDB Y cable disconnects the wire channel going to the 2d piezo in the HDSI ...and redirects the wire channel to the 2d piezo in the Dual Beam ... It is wires ...no "switching" involved ...
If you did not get 2d when the Setup was completed ...either...:
*The AS SIDB Y cable is bad ...
*The Dual Beam xducer is bad ...
*The Dual Beam cable is not fully seated in the AS SIDB Y cable connection ...
Rickie