After reviewing this link on WB sensor circuits and sensors again:
https://www.aa1car.com/library/wraf.htm

….I noticed that sensor life will shorten if the heater circuit voltage (thus current) is not regulated or non-existent, so it’s not a simple matter of switching all sensor leads to the gauge back and forth. Manually swapping WB sensor connectors to the gauge can work, but the inactive sensor will be compromised by its inactivity.

According to this:
https://www.youtube.com/watch?v=ge2O3bVxftQ&feature=emb_logo

The sensor's heater circuit voltage is Pulse Width Modulated (PWM) regulated so the heater current is a constant 3 amps. In a standalone WB sensor circuit, independent of a vehicle's ECM, the PWM voltage control is contained within the WB gauge.

It seems in order to manually select the A/F sensor from either bank (we’ll label the sensors “A” and “B”) to display onto the one WB gauge, one could manually disconnect and connect the sensor harness to the gauge. A basic multi-pole, multi-throw switch could also do that with a flick of a finger. In either case, the issue is how to keep the “inactive” (not selected) sensor within spec whenever the engine is running without damage or contamination. IOW, both sensor heater circuits must remain operational when the engine is ON.

Thus, while displaying the A/F on WB sensor A, can an external PWM voltage source alternately control the heater circuit of WB sensor B and vice versa regardless of whether sensor A or B is selected? There may be additional issues as well TBD.

Forgive me. My electronics expertise doesn’t extend far enough to confirm this. EEs and others more advanced are welcome to chime in and assist….

LSU 4.9 sensor connector:
http://forums.pelicanparts.com/uploa...1613857036.jpg

Thanks,
Sherwood