2000chevy silverado 02 sensor no activity

The grounds on the ecm are good
I checked them multiple times .
Pin 40 pin 1 both blue and red ecm connectors have a good ground.
No activity on bank 1 sensor 2.
If i add a ground to pin28 tan white wire
Bank 1 sensor 2 drops from 440 to 0
On my scanner and i get a good signal .
So if the grounds are all good going to the ecm why would it not work .

Not having your wiring diagram to follow puts me at a disadvantage.

I have to ask though, you mention grounding the signal wire for the sensor and it drops from 440v to 0v (not saying that's wrong), so what is; "On my scanner and i get a good signal" What's the good signal?

Downstream 02's do not oscillate like upstream do (200-800mv), instead they report a steady voltage... 650-750mv. 440mv is most likely the GM bias voltage of 450mv if you're testing the sensor cold... not sure which way you're doing your testing. Have you tested or are you testing at the sensor connection?

Sorry i used the word signal as in i am getting a reading of 700mv.it bounces up then back down .

I have an autel scan tool hooked up monitoring the bank 1 sensor 2 .
If i unhook the ground wire that i am using for testing the scanner jumps to 450mv and just sits there it with bounce between 435-452 mv .
When i hook up the ground the scanner immediately drops to 13mv and will jump up to 700mv if i give the engine throttle.

The (MIL) shut off it never shuts off in the 3 years i have had the truck if i unhook the ground i made bank 1 sensor 2 immediately jumps to a steady 450mv and the (MIL) will illuminate after driving around for a bit and i get the same code p0140 .

I would suggest that you remove the proxy ground wire then swap B1S2 and B2S2 sensors and retest (without the proxy ground). Did the problem move from B1 to B2? If it moved, the sensor is bad. if it stayed, wiring (ground in this case) is the problem. One last thing... was B1S2 replaced at any time? is the connector the same as B2S2?

So i switched B1S2 OVER TO B2S2.
The computer now reports insufficient activity B2S2.(i replaced the sensor with a denso)

B1S2 was replaced with a brand called NTK
i had Denso sensors on the truck i am not sure what shop installed those sensors. I no longer need the Proxy ground.

So the original sensor which were ac delcos B1S2 threw a heater circuit code i took it to a shop they replaced it with denso sensors .
Then shortly after i got a p0140 i took it back to the shop they had my truck for 1 hour.
When i drove off no MIL light came back on.
I took the truck back they got very rude with me and told me they already changed it twice it had to be a bad wire or ecm.
So i took it to another shop they asked what i had done i told them they suggested an ecm reprogram did that no fix .
This is why it was driving me nuts .
To cut the story short i then brought it to a few more shops and thats when they really got me the truck is basically new under the hood every sensor was replaced .

Don't be a parts changer sticks out so good on this .

Thank you sincerely .

Your diagnosis saved the left leg and arm i still have the shops would have taken them to lol .

The tricky part with the 2000-2003 is if the 02's are case ground or isolated ground. You mentioned Tan/Wht wire, that moved me to a case ground 02. The 02 is internally grounded to the 02 housing. Have to have the correct type 02 for those years. Prior to 2000 they were case ground. After 2003 the are isolated ground.

Glad you're fixed