Have been trying to trouble shoot issue with short term fuel on B2...swapped o2 sensors and high reading was same on B2 (guess eliminated sensor as the problem) Did wiring check from harness conn to PCM pins all ring good and correct. Have high reading on B2 (99.2% see pic)) with engine off, o2 sensor disconnected. When running o2 readings on b1 0.445v steady b2 - 0.45 - 0.85v bouncing. The PCM is a GM truck 98-2000. Not sure what this means, any advice appreciated.

 

When the engine's running, what are the fuel trims? This should be represented in the form of percent, for both long and short and both banks.

Not sure what you're trying to achieve by reciting your trims on a non-running engine.

What exactly is the problem?

 

.445v is what they read when disconnected.
Disconnect the other side and watch what it reads.
STFT maxes out at 55%. When the LTFT is maxed at 25%.

What do the LTFT read?

That 99% seems like just a function of your tool.