0411 PCM voltage going to O2 sensors?

Hello everyone! I have a question with regards to 0411 PCM's. As many of you know, I converted my Trans Am with a 0411 PCM for my LT1. I have been having issues with my O2 sensors. the bank 1 sensor 1 keeps throwing a code for sensor inactivity, I have changed these multiple times now, and the problem persists.
while I was trouble shooting the sensors, I used my multimeter, on millivolt setting, probing the pins going to the PCM, it wasn't reading the usual .100mv to .900mv reading, I was getting 4.5 volts, is it possible my PCM could be bad? I tested the sensors off the car, they increase and decrease in voltage from .100mv p to 1.0volts up and down. could be possible I have made a wrong pinout change?
I'm going to check the harness at the PCM (disconnected) to see if the harness has voltage at the O2 Sensor High/Low pins.
this car is driving me nuts, should have been a slam dunk conversion, but I've obviously done something wrong......
let me know what you guys think.
Thanks!
Ben Smith

Here is what I have on the pinout for the 411 O2 sensors.

connect pin 28 and 29 additionally to ground!

The PCM will put 0.45V onto the pins when an O2 sensor is not connected. Maybe you don't have a connection between the O2 sensor and the PCM pin. Double check your wiring.

To further what mecanicus posted, the negative side of the O2 sensor element should be connected to the sensor case inside the O2 sensor, but some O2 sensors have been found to not have that connection. The PCM won't work without it. See the "case" jumper inside the O2 sensor.

Thank you all for the replies. I will add the grounds to the two pins, (26&29) and just so you know, I was reading “4.5 volts” at the high signal pin wire(purple /white wire at pin 69 C1 blue connector) not the .450mv you mentioned, leading me to believe I made a wiring mistake.
I went over my pinouts front to back, front to back many times, so I doubt that is the case. I will disconnect the PCM from the harness, and verify all the powered connections, and the O2 sensor wiring for positive voltage at those pins. I even swapped the PCM to see if I had the same situation, and it does. So, back to chasing “Gremlins”
Thanks!
Ben Smith

Well, only ground the pins if they are not already connected to ground internally in the O2 sensors. Otherwise, you can cause issues ranging from noise to those wires melting.

Ok, yesterday I replaced both of my O2 Sensors, I think my bank one sensor wire harness has a break in one of
The leads between the PCM and the sensor.
But I got the bank two sensor reading like normal, what a difference in the way it runs, now to trace out the other side,
Probably tomorrow evening.
I pulled two plugs out to see how they looked, even though its running like crap, the insulators are a darker tan color,
So, once I get the other sensor reading I’ll let you all know what I find.
Ben Smith