Quick question for you. With key on engine off. Should I just see the Voltage bias on the scanner. Also should that decrease at all with the engine off. Also, if I front probe the B1S1 harness green/white wire should I have battery voltage there all times? Lastly you want me to just check for a drop on that wire from one side of the connector to the other correct?

 

Just some more observations. Ive triple checked the wiring and to the best of my knowledge there are no faults there. If i allow the truck to warm up i can clearly see bank 2 switching properly between 200-900mv while bank one is roughly 350-800mv. Sensor 2 is operating properly as well. Fuel trims on bank 1 are roughly -3 while bank 2 is flat to about 2%. Truck runs good just tiredof looking at this dumb light.

 

Rather than answer and confuse you, do you mean the O2 output or the heater circuit?

No. Key must be in the run position, engine running or not, it will only show battery voltage when the PCM determines that the O2 sensor is not up to temperature and not producing voltage.


Yes, one DVOM probe on each side of the connector, as close a possible to the connector. Key on, engine off, it must be less than .1 volts. If voltage is higher, the connection is poor. Remember, we're looking for a small problem, it's not going to be 12 volts Afterall, the PCM is getting a signal, maybe just not good enough... we don't know what the problem is, we're still looking for the proverbial needle in a haystack.


Granted, it was a "rough" estimate, but at the time you checked it, bank 1 was averaging .580 volts and bank 2 was averaging .550 volts, virtually the same. Target voltage is .450 volts, so both banks were running a fuzz rich. In the "Diagnostic Aids" section of the flow chart, https://blazerforum.com/forum/diagno...plained-30095/ it lists some things to check. You can rule out anything that would cause a lean condition, such as a vacuum leak, etc.