Subaru: Subaru Engine Check Light and the little green wires...

I am a recent Subaru owner and have just discovered something I think
other Subaru owners would appreciate knowing. This may have been
covered before in other post but it is worth mentioning once more.

I bought a used 1998 Forester S (2.5l) with 110000 km last December. So
far it has been a good experience excepted for the engine check light
turning on last March. Replaced the emission bypass solenoid, the bill
was about $500 CAN, parts and labor included.

Over the past weekend I was vacuuming the car before putting one winter
rubber mats. As I was leaning over to place the mat under the pedals on
the driver side, I discovered a green wire with a connector which was
left unconnected! The first thing that went through my mind was to
connect the wire and find out what was not working. As soon as I turned
the ignition, the engine check light was flashing like a Christmas tree.
I immediately disconnected the wire and turn the ignition on once
more, the engine check light was off. At that moment I was cursing the
Subaru dealership that "repaired" my car last March, I was sure that
they tricked me by simply disconnecting the engine check light wire.

Come Monday, I drove to the Subaru dealership ready to give them a piece
of my mind. I tell the service guy what I discovered, he then tells me
that this is some kind of "secret" and "for service mechanics only"
green wire that should stay disconnected and that if it was to be
connected, the engine check light was going to blink. Anyway, I told
him that I read the owners manual from cover to cover and did not see
anything about a green wire that should not be connected. He tells me
to thrust him. So I didn't. I drove across town to the other Subaru
Dealership, walk up to the service guy, he tells me about the "secret"
little green wire that should never be connected... Turn out the first
guy was not lying.

My faith in most people being honest has been restored but beware of the
green wire. They both told me that if connected, the car could go into
hibernation mode and loose all power. I am thinking that if connected,
it would unlock 100 more horsepower or something like that .

bao