1985 Toyota Corolla GTS door wire

Hey, the wiring info says

DOOR TRIGGER|RED / wht or blk/wht |- |plug at fusebox |

 Fuse box usually mean the one on the engine bay then?  Because there is one inside the car by kick panel too, but then the other wire say driver side kick panel and I found that one. 

I guess I will need to run a wire through the firewall and mess with the engine fuse box.??

How come there isn't one inside the car..?

Can someone help me out.?  I find one of the red white wires.   (there are many plugs on the fuse box with a RED / white to it!)

I pulled the plug off, and measure the pin on the fuse box directly.  It does get grounded when the door is opened.

And so I put the plug back on, and measure that wire, it does not get the same result!   So I found that wire actually supply a voltage to this pin.   When the door is CLOSED it normally have 12V running to it, when the door is opened, then it measures 0.7V., and the "door" light on the dashboard come on.  When I removed this plug it does not come on.

I found another wire on another plug that is the same.

This wire should be the circult for the "Door" light on the instructment cluster.. getting close but not really what I need??

I just about probed every single color RED / white and black white and this is the closest that I came to.  Is there a way to make this work with a diode or something to isolate the ground further?

I have the factory wiring diagram it says it's RED / white wire also.. but this dash circuitry seem to be messing me up.

Thanks in advance. 

I'm getting so desperate I almost going to tap the wire at the door switch or dome light, that should work for sure then.??

The car is a 1985 Toyota Corolla GTS.

I talked to my EE at work?   It looks like I might be probing the right thing wire??

It has 12 volt because it is the negative side of the door warning light bulb?

And I can't test for continuity properly while there is voltage running through the stuff.