Okay i bought a heated oxygen sensor (delco) off ebay and i need to know how to wire it up. I've been having problems with the new Bosch sensor in there keeping the car out of closed loop. First noticed it when my gta started drinking gas and confirmed it with an auto xray. I know the 3 wires are for the ECM, and the heater element power and ground wires. I can splice the connector and connect the ecm wire to my harness and could easily wire a relay and a switch in my gta to manually turn it on and off. But is there any relatively easy way i can have it so the sensor would be activated when the car is on, or even better, turn it off when the car goes into closed loop?

 

Let me see. I can't remember what color the wires are, but regardless of their colors, 2 will be the same color and the third will be different. I think there's 1 black and 2 white, but I can't remember. The "different" color is the actual sensor wire that needs to be connected to the original pink o2 sensor wire. The other two are power and ground. What I did with mine was to buy the female GM-style plug that connects to the new oxygen sensor. I cut the original plug off of the car's harness and wired in the 3 wire plug. I ran the other 2 wires up through the loom tubing to the fuel pump relay, since the stock sensor wire goes up there anyway. I tapped the power line off of the output side of the fuel pump relay (It was either the A or E terminal - you'll want to check that with a test light or volt meter - instructions below*) and wired the ground to the bracket that holds the fuel pump relay to the firewall. When I finished, it all looked 100% stock, and allows me to change sensors without cutting any wiring.


* Fuel pump relay testing instructions. If you look at the fuel pump relay, there will be 5 wires going to it. 2 fat ones on the ends (A and E pins) and 3 thin ones. If you're using a test light, stay the hell away from the thin green wire!!!!!!! You'll fry your ECM like I did the first time. Anyway, with a test light or VOM, test the outer two wires with the car turned off. The one that lights up is the constant feed and NOT the one you want. Verify that the other one is on only when the car is running, and for a few seconds when you first turn the key. That's the output side of the relay and that's the wire you want to tap into for the oxygen sensor.

 

While hooking into the fuel pump relay is a clean trick way to do it, it can be hard to get to the wiring easily (if you're not a professional stereo installer that is, lol)

You can hook the power to any on in run circuit you want. The easiest place to do this is right at the fuse box itself. IIRC they don't draw much current so you won't need a relay to run it.

 

To be honest Ed, I think tapping into the fuel pump relay has got to be easier than fighting with the rat's nest at the back of the fuse panel, plus it saves you the hassle of running it through the firewall. But, Ed makes a good point in that basically you can use any power source that is on when the car is running. You don't want to necessarily use ignition power though, because then it'll be on if you turn the key back.

 

Do a search for ho2s in the General tech board, covering the last 6 months.

You'll find a thread started by Paul Riccoli, look for Vaders reply. I think it's exactly what you want...IIRC, he tapped into the EVAP purge signal from the ECM to control the relay, and explains how it works.