well the verdict is, the output measured from WB output to electronics ground is actually very slightly above 5V I measured 5.04V at these points as well as the WB output and ground plane on the ECU itself.
now the interesting part is, that is with the WB output free floating and not connected. as soon as it is connected its drops to 4.96V. So the ECU analogue input is sinking the voltage slightly.
Even more interesting is, I had a needle pushed into the WB output wire so I could measure while it was connected to the ECU. I discovered that the tyres in the car are conductive
If I touched the wire while isolated from the car and standing up with my boots on, there was no additional drop, WB reading sat at 18.8AFR, soon as I also touched the ground with my hand or knee or any part of my skin on the floor the voltage dropped some and the AFR dropped by 0.5AFR
If I touched the grounding point on the car so I added a circuit from WB output to the body ground through my own body, the same amount of drop was seen. When I touched only the WB wire and the concrete floor with my skin without touching any part of the car, its concludes the tyres are somewhat conductive, and so is the concrete lol.
Conclusion from that is, the WB output is very very low current and takes virtually nothing to drop the voltage. Given that it actually is outputting a very accurate 5V more or less at full lean, should be able to adjust the AFR @ 5V setting until it reads 20. I adjusted it to 21.4 to get it to read at 20. So hopefully is will be more accurate now?
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.