4 Wire O2 Sensor Bypass Diagram. This rear oxygen sensor wiring diagram includes the following circuits. O2 simulator tester gm 4 wire general motors 1996 2003 the o2 simulator is a plug in replacement for the secondary o2 sensor that will provide the pcm with a signal that emulates a healthy cat for testing and off road purposes.
You will now need to remove the sensor. Update tested the 4 wires coming from the truck side harness main o2 sensor and have 1 hot wire 35 85 2 wires with 1 and 1 with 1 3 volts. Making your own rear o2 bypass simulator.
One of the wires will always be the signal voltage.
A four wired oxygen sensor has four wires two wires for the heater circuit and two wires are for the sensing element. Ats can give you the wiring diagram to check so you dont have to guess. You can find the front o2 sensor circuit diagram here. Gmt 800 older gm general discussion help.