o2 Sensor Wiring Issue

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dahomietaz
Posts: 6
Joined: Sun Feb 11, 2024 2:59 pm
Car: 2007 Infiniti G35x

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Hello to anyone reading this

So I have a 2007 Infiniti G35X and both of my upstream o2 sensors aren’t reading. So I thought the sensors were bad so I replaced them with OEM. They still weren’t reading so then I replaced the fuse 15A for the o2’s in the IPDM behind the battery and the o2’s still aren’t reading.

But I noticed that the short is so bad in the wiring that I can install a new fuse, start the car and turn it off and the fuse in the IPDM will be blown instantly. I did it 3 times to make sure LOL. All 3 of the new fuses just blow instantly when you start the car for the o2’s.

Any Ideas on where to start???


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VStar650CL
Technical Expert
Posts: 9567
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

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Unless a sensor is shorted internally, the only things which can short on the power side are the heater wires. Those use PWM, the heater has power at all times and the ECM grounds the other side in pulses (PWM) depending on the amount of heat needed. The 12V supply feeds all 4 sensors, front and rear. Try disconnecting all 4, if fuse 46 still blows then the issue is in the wiring, if not then a sensor is shorted internally. In the latter case, plug them back in one at a time to locate the culprit.

dahomietaz
Posts: 6
Joined: Sun Feb 11, 2024 2:59 pm
Car: 2007 Infiniti G35x

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So i think there’s something wrong with the heater wires in the upstream. Cause i do know that on both D/S & P/S both heater wires are yellow in the upstream. And they go straight to the fuse box and the fuse blows everytime the car gets to operating temp. And i don’t think there is something wrong with power or signal because i can see the number fluctuating on the data log. It just seems not to pick up heat cause it blows the fuse. Has no way to read it. So the D/S connects to the P/S at some point with the yellow and then turn into 1 wire and run straight to the fuse box and eventually split off again at some point. 1 wire remaining yellow and the other one turning purple. So the yellow wires go from 2 to 1 and back 2. Yellow Bank 1 Sensor 1 & Yellow Bank 2 Sensor 1 turn to a Single Yellow and then turn into a separate Yellow & Violet at some point going to two different blocks.

https://www.nicoclub.com/service-manual ... 007/ec.pdf

On page EC-503 in the diagram for SENSOR 1 BANK 1 & 2 you can see both banks Terminal No. 4 come out as yellow and then join each other to make 1 wire (which is wire 30) and wire 30 singles itself then splits off again to Connector No.’s F1 and E3 which you can find Connector No. E3 on page EC-507 which turns into Violet BUT on Connector No. F1 Terminal 30 on page EC-510 it still remains yellow.

I also do not know where to find Connector No. F1 & E3 for Terminal 30 on both Connectors. Is it the fuse box or near the ECM?

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VStar650CL
Technical Expert
Posts: 9567
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

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You need the PG section of the manual for that:
https://www.nicoclub.com/service-manual ... 7%2Fpg.pdf

PG has all the harness layouts and all the power supply and ground diagrams. The power diagrams will show you the entire power path from the battery on down, and the harness layout will show you exact locations for every connector on the car.

dahomietaz
Posts: 6
Joined: Sun Feb 11, 2024 2:59 pm
Car: 2007 Infiniti G35x

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Thanks boss!!! I was able to locate Connector No.’s F1 & E3. I would’ve never found it. You are a GOAT.

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VStar650CL
Technical Expert
Posts: 9567
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

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:dblthumb:


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