i have a 3.4 liter vs and i need to know the location of the o2 sensor ground wires

Majority, or all, of GM O2 sensors are one-wire type. The body of the sensor is ground. I could be mistaken.

what yr car???3.4 was a later model motor, and if 95 up, will have 4 wire...there will be 2 grounds on a 4 wire...1 for the heater, and 1 for the sensor, i believe...the sensor ground, if not mistaken goes up to a pigtail at the ecm...but dont quote me on that...best to get a schematic from alldata for it...