What's this cable??

mmm base boost
that how I check if the wastegates working
but it is plugged in
the apc is mounted on the radiator
and has three hoses that run to it (it is plugged in just not shown in pictures due to the fact the car is only half back together)

thats just the solonoid, there is controller for that. your cars older right, as in not T5? i am pretty sure you have a seperate box for the APC. its under the seat or kick panel or something.

Under the seat I believe (i would have to double check the saab site as I havent sought it out yet)
And the APC is plugged in
When I disconnect the solonoid I only get base boost
and with it plugged in I tend to overboost (vaccum leak/bad solonoid)
I think it might be a bit of both

I thought you meant that plug would run to the solonoid (it does have one)

then it must be for the canuter valve

possibly diagnostic link/harness?

either that or I’m gonna guess something with alarm