What's this Wire?! (Speedo)
 

Hi All, I replaced the speedo convertor in my 2005 STI today as I was getting frequent faults where my speedo would sit at 0mph whilst driving. The swap seems to have solved my issue, but I'm curious about how the old convertor was wired in.

My new one uses four wires:

12v Ignition
Ground
KPH In
MPH Out

Pretty straight forward!

The old one however used five...

12v Ignition
Ground
KPH In
MPH Out
???

The ??? one is pictured here, it's the fourth in from the right on the connector which is labelled in the service manual as i11 I believe. I'm a bit rubbish with the service manuals though, so can't work out what it actually is! It's a Green/White wire which to be clear is different from the Green/Yellow which is the speed pulse wire.

https://lh3.googleusercontent.com/-k...788/speedo.png

Any ideas? I'm just curious!