Hi Robert...

Leave the sensor connected. It will be either three wire [heated] or
one wire [unheated]. Assuming that no one has muddled with the wiring
the white wires are for the heater circuit and the black wire is
signal. Run the engine to operating temperature and probe the black
wire. You should see a fluctuating signal between 200mv [lean] and
800mv [rich] switching at 5 or more cycles per second. Most voltmeters
will not read that quickly so your sample rate will not follow quite as
well but should give you an idea of what is happening. Do this at idle
and at 2000-2500RPM with no load and also, if an automatic, in gear,
brake applied. What you are looking for is the numeric equivalent of a
nice, even wave.

I may have some basic procedures at work and will email to you if I
find some.

Regards

wharf rat    dupree8995@msn.com