Quick question …
Looking at the color coding for the wires going to my 1989 XJ40’s ECU I see that the signal wire coming from the O2 sensor is labeled “INN”. This designation doesn’t show up in the color codes for the wiring.
Any idea what “INN” stands for ?
My Haynes manual says NCA which means No Color Available.
Joe …
I see that, thank you. Cross checking with my Haynes manual it does show the color code of the signal wire going into the ECU as NCA (hmm, I still wonder what INN stands for on my Jaguar shop manual ?) Perhaps ir’s some type of shielded wire ?
If we were dealing with a Fiat I would say “Itsa Notta Noted”.
FamG: Boopa-dee Bappa-dee
Ifound a link that shows that to be somesort of option can conect with a white wire I copied it to clopboard but there it sits because I can’t find clipboard on my phone, sorry, but it is also inn
Al-l-righty then …
Well I finally got around to digging out my engine’s ECU. Actually I was a little surprised that it was located under all the spaghetti of wires and relays and not buried behind them (if you’ve been there you’ll know what I’m talking about).
Anywho … I’ve ordered 2 (count 'em 2 with the exact same part number) used ECU’s to do some product replacement troubleshooting trying to solve my O2 sensor check engine light.
So next week when I have the replacement ECU’s in hand I’ll pull out my original ECU and plug in the replacement(s) and see what happens …
I SHALL NOT BE DEFEATED 
Know the feeling …you’ll get it - eventually!