Mm...seeing as I didn't send you the locking tool in time, I thought I'd spend 10 minutes researching this for you.
Quick searches for GRN/WHT in the manual comes up with a mix of things, amazing how many items use this colour wire. There is the fuel sender gauge wire (obviously not that), brake lights/brake switch (probably not), cruise control (no, also to do with the brake switch for cancelling), Auto transmission gear position (assume not as yours has always been manual right?), seat heaters (you don't live in Canada or Russia!

), power door lock module (in the door, so clearly not).
Likwise the RED/WHT, comes up with MAP sensor (could be, in the right area?), EGR valve (could be, in the right area?), ABS pump motor connector (this could be the culprit, the other wire is just GRN though, you sure it's GRN/WHT?), dash light brightness controller (nope).
So based on the above I'd say ABS pump motor connector and there is no white on the GRN? My ABS connectors plugs were welded shut on mine and I ended up cutting mine, so could see you doing the same. After spending 10 minutes swearing and battling with a damn plastic plug, I figured I'll never need it again as I'm removing it, let's just cut the bugger off! Sound like a familiar thought?
If I was at home right now I could check the proper wiring diagrams in my UK hard copies, but 99% sure that's right. Here is a screenshot of the connector in the electronic manual:
