Hey guys, I did a dumb thing. I was cleaning my O2 sensor connectors in the engine bay. Realized I had not noted which O2 goes to what connector. The connectors on all 4 are the same. Is there any easy way to determine which conn is for the upstream & downstream? I noticed one of the cables on the pass side has a blue wrapping around it. The drivers side one has blue tape maybe from when I had the 15K done. I suppose I could did into the wring diagrams and do continuity checks to the ECU if it boils down to it. Help! Mike 1999 F355 spider. 19/100
Unfortunately a lot of the harness is sealed, so it's probably difficult to see wire colours. Anyway, here's the diagram... 5.2 Wiring Schematic
I am not sure if you mean the same, but the upstream (pre-cat) sensors are identified by a blue ribbon/tape on the connector cable.
The wring harness with the blue tape goes to the front cat sensor. If you have no blue tape, find a post where I posted the ECU wiring and find the one signal to the front sensor and find that wire. The rest is then easy.
Yes there is blue tape on left and right sides. That's what I thought. I'll confirm it with the wiring diagram to the ecu. Thanks.
The wiring diagram is nice but Yelcab has an ecu pin out and it conflicts.regarding the bank 2. The sensors are opposite. I mean upstream and downstream. Now I have no idea what the hell is correct. I have cel codes shooting out like a machine gun. The ecu pin out shows bank 1 and 2 upstream O2 sensors have a green wire on the signal output. The wiring diagram shows it on the downstream sensor. What a nightmare. Can anyone physically confirm what is what?
Yelcab has a post with a sweet ECU pin out. Problem is that the upstream and downstream O2 sensors are opposite in these two diagrams. One is wrong. Which one? The ecu pin out shows both upstream sensors having a green wire. That is logical. I would tend to believe the ecu vs the wiring diagram. If someone could look at both bank upstream sensors and see if that green wire is there. On mine there is just enough exposed wire coming out of the black sleeve to see the four wires. I sprayed a little simple green to wash off the grime to see the colors better. Help!
Sorry, Yelcab's is correct. I compared it with a pre-production diagram produced by Bosch. I'll amend the diagram shortly. Thanks for spotting the error. Cheers
This should clarify it for you. The blue banded lead goes upstream The upstream lead (blue banded) has a lime green wire and a black with red stripe wire and two brown wires. The non banded lead goes downstream The downstream lead has an emerald green wire and two brownish wires. It may have that black/red lead as well. See pic below Image Unavailable, Please Login
Also, you might check that the correct o2 sensors were installed in the correct positions. If someone screwed up the connections they may have screwed up the install as well. The upstream sensor has four wires the downstream sensor has three wires.
This wiring diagram does not match mine. Can you tell me where it came from? Mine is dated from July 1997 (USA version) Spider. Do you know if this is valid for USA 5.2? Thanks
This wiring diagram does not match mine. Can you tell me where it came from? Mine is dated from July 1997 (USA version) Spider. Do you know if this is valid for USA 5.2? Mike
First photo is drivers side, second pass side. Confirm pass side blue tape is pre-cat? Image Unavailable, Please Login Image Unavailable, Please Login
Right/starboard side. Same as port side. Blue band to upstream sensor. Light green wire in blue band bundle. Dark green wire in non banded downstream bundle. I see that qavion has a ? On his wiring diagram for that dark green wire on the downstream sensor. He also has only one green on his color coding. Those greens are definitely different as you can see in these pics. Image Unavailable, Please Login
Better pic of wires. In this pic of right side, both bundles have the dark green wire and upstream has the light green one. This is different than the left side above. Image Unavailable, Please Login
Unfortunately, the Ferrari diagrams only show one type of green colour in their colour coding system.. i.e. V = green, so I can't explain the different greens on the car itself. Coincidentally, I have a brand new engine harness from the factory ready to install, but, to add to the confusion, this only has one green wire (amongst all four O2 sensor plugs). What I have on the car at the moment, may be like yours, however. I don't know for sure which is left or right on the new harness, but there is blue tape on one of each pair. Even new, the colours are hard to pick.... Pair 1 (probably L/H): Blue tape: (A) green (0.5mm), (B) violet, (C) Brown, (D) violet/black (0.5mm) Non-blue tape: (A) violet (0.5mm), (B) pink or very light violet, (C) Brown /black, (D) violet/black (0.5mm) Pair 2 (probably R/H): Blue tape: (A) violet (0.5mm), (B) violet, (C) brown, (D) violet/black (0.5mm) Non-blue tape: (A) violet (0.5mm), (B) violet (2.0mm), (C) brown/black, (D) violet/black (0.5mm) The only colour I seem to have wrong on the diagram vs the new harness is the R/H upstream green colour. I would have to do resistance checks on the new harness to confirm this (Sorry, I'll be busy for the next few days). My latest 5.2 Diagram You may have to refresh your browser to see the latest image (I've added question marks). Cheers Ian
