Hi Mark,

Are you sure this has an earth bias? I didnt think it had.

If it has an earth bias when it is switching within spec, as Steve saw on Vag Com, then it is even stranger that the signal voltage climbs about .25 volts.

Either way Steve needs to check if the signal level really matches what live data is showing him, and if so, where the extra voltage is coming from.

Steve, assuming there is a ground bias, scope/measure while it is switching normally to check this and check again after it goes high.