Heated 02 Sensor (1 wire to 3 wire Conversion) wiring suggestions.

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Big D

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I purchased a 3 wire 02 sensor off of SPR Performance. it has a nice little connector for 1 wire to connect to the original 1 wire connector and 2 other wires. 1 goes to ground, which I was going to connect to the frame. The 3rd wire goes to a switched 12 volt, I found multiple wires that show 12v with the truck on, but I just dont like the Idea of splicing into another random switched hot wire.

Those who have made the Conversion, where did you get your switched 12 volt source?
 

magimerlin

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What year is your truck? On my 94 1ton I had, I just connected the power wire to the power junction box/bar on the passanger side fire wall..

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Big D

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the junction box power bar shows 12v with the truck off. theres is a fuel pump fuse and a relay in there, I guess ill splice into that until I can do it a better way.
 

SKFengineer

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Picking up an old thread. I'm doing the same exact thing, 1 wire to 3 wire conversion since I installed headers on the truck. I was going to tap into a power source on the firewall junction box but I assumed that was a "fused" source and therefore I was wondering if the heated O2 sensor would over load the circuit. Last thing I need is to start popping fuel pump fuses while driving down the road. Anyone have experience here?

Thanks
 

delta_p

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Picking up an old thread. I'm doing the same exact thing, 1 wire to 3 wire conversion since I installed headers on the truck. I was going to tap into a power source on the firewall junction box but I assumed that was a "fused" source and therefore I was wondering if the heated O2 sensor would over load the circuit. Last thing I need is to start popping fuel pump fuses while driving down the road. Anyone have experience here?

Thanks

I haven't done this mod. But you should be able to measure the resistance of the heater in the O2 sensor, across the wire your hooking to the 12V and the wire that's gonna get grounded, or the O2 body. Normally, it's around 11 to 15 ohms when cold on a good unit. So the current through it should be about 1 - 1.3 amps at 14V when turns on. Each one off the same source would draw that when turned on. The resistance will go up when the sensor gets hot.
You can probably measure the current through the fused source, figure the extra amps from the number of O2's, and check the fuse rating against that totaled.
 
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SKFengineer

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I just have the one heated O2 sensor. I'll check the resistance as you note but just for conversation here assuming my resistance falls within the value you offered and I have one 02 sensor it's somewhat safe to assume about 2 amps of draw if you add a little for the sensor getting warm and the resistance increasing.

Thanks
 

PlayingWithTBI

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I just ran mine off the ignition switch through the firewall and with an in-line fuse. I have the 3-wire NBO2, a WBO2, and its control module on that circuit.
 

Supercharged111

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I haven't done this mod. But you should be able to measure the resistance of the heater in the O2 sensor, across the wire your hooking to the 12V and the wire that's gonna get grounded, or the O2 body. Normally, it's around 11 to 15 ohms when cold on a good unit. So the current through it should be about 1 - 1.3 amps at 14V when turns on. Each one off the same source would draw that when turned on. The resistance will go up when the sensor gets hot.
You can probably measure the current through the fused source, figure the extra amps from the number of O2's, and check the fuse rating against that totaled.

It's been a while, but I'm pretty sure I took the half-ass approach on my '88 and just tapped into an existing source. It never gave me any issues. Present day me would prefer something more professional, but that was 2009 me in the driveway in the middle of a UP MI winter so the easy was was it for me.
 
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