I need help troubleshooting a 4 wire O2 Sensor. I did an internet search and got conflicting information:

Black wire1: Heater element neg
Black wire2: Heater element 12 VDC
Gray: High output signal (ECM)
White: Low output signal (ECM

or

Black wire1: Heater element neg
Black wire2: Heater element 12 VDC
Gray: O2 ground
White: O2 signal

Please advise, I need to know to properly troubleshoot the my O2 sensor & harness.

 

I would go with the grey as the high output signal to the ECM, 02 sensors produce the referance voltage that goes to the ECM. So it would not need a ground.

 

the first link on this page has a o2 section and how to test them

 

youngfordguy, thanks for the info. I scaned through the O2 troubleshooting pages, but only notice 1 wire and multi wires up to 3 wires. My bronco II is a late model 89 and the wiring harness and original O2 sensor have 4 wires vs 3 wires. That fourth wire (orange) is the wire in question. On my buddy's 89 bronco II, he only has a 3 wire harness and 3 wire O2 sensor and the orange wire coming off of the ECU harness is grounded to the vehicle body. I was planning to do the same and get a 3 wire O2 sensor.

 

The fourth Orange wire is the Ground wire from pin #49 of the ECU Computer.

 

ok ithink i got it here. the BK/LG wire is a ground. the DG/P is the wire that send info to the computer. the GY/Y is the power for the heater and and i can't find what the orange one dose

 

Computer pin # 49 Orange Wire (O) HEGO GROUND
Computer pin # 29 Dark Green with P stripe (DG/P) HEGO Information
Gray with yellow stripe IGN RUN Circuit
Black with green stripe Power Ground.
Image:
http://i54.photobucket.com/albums/g9...CM/HEGOBII.gif

 

What can i do if my wiring that goes back to the o2 sensor plug in is is lost? 90 ford f150 302.

 

You are posting in the Forum. This is the BII Forum.

What year is your F-150?