oxygen trouble

[monette999]

I have a '97 Blazer.

4 total oxygen sensors.

B1S1 is the driver's side of the y-pipe,
B2S1 is on the passenger side directly ahead of the 'y' in y-pipe on the passenger down pipe. B1S1 & B2S1 directly influence the fuel delivery of the vehicle.
B1S3 is the post-cat sensor.
B1S2 which is a pre-cat sensor.
My B1S3 shows low voltage. Need to see the vehicle body side pinning.
Where is ground and supply. I already swapped o2 sensor.

the level is constand low compared to the B1S2.Thanks for the help.

regards bob