I have Nissan service manual, and on the 2nd volume, they talk about the O2 sensors. One of the cables supposes to be L/Y, meaning light yellow right?

I can't find that cable, and I'm not sure of cutting anything before clearing this out.

 

Yea, I think that's what it means. I have a L/B meaning light blue. Are you sure it's talking about the downstream O2 sensor?

 

If you go tho the service manual, EC-163, you will see the diagram. What is really wired is that the O2 sensor that I have from Nissan only has 3 colors. Black, grey and white(2 times).

 

That's the colors for the O2 after the last harness to the O2 itself. Look for EC-242 and 244. This is what I have a copy of. This will show what I've been telling you the hole time. It has the colors of the wires and what they represent. After you identify, just follow the wires through the harness and then you can tell what the B, G, and two whites are.