To add to what Ron has contributed here, I am providing a wiring diagram
The powertrain control module connector is circled on the next diagram. You can only see the connector on the firewall. The pcm is inside the vehicle on the other side of the firewall.
This is what the pcm conector looks like.
Just to add to Ron's answer, you could also test the o2 sensor heater circuits for complete failure by using a testlight
Hook up your testlight to BATTERY +. Touch the negative terminal at the battery to make sure your testlight works.
Turn the key off. Unplug the o2 sensors. Start the engine up.
Take your testlight (still connected to BATTERY + ) and touch it to the terminals for the oxygen sensor heater control wires going to the computer . Y/LB, R/W, W/BK.
If the testlight does NOT light up, there is no ground circuit for the heaters. You most likely have a damaged computer. Check the continuity of the wires back to the computer (with the computer disconnected) and if the harness pins look good. Order a new computer.
Note: if the testlight lights up, you may still have a problem with the computer. The o2 sensor heaters can consume 2 amps or more when starting up. The testlight is 1/4Amp or less.
I hope this additional information is of assistance.