Isolating door triggers problem

Ok, I found 2 wires,

one is ground when passenger side door is opened.

another is ground when driver side door is opened

Now I try to do this..

https://www.the12volt.com/images/doortrigs.gif

soldiering one diode into each wire and joining both wires at the black end.. which will be going to into the alarm later..  It is not working.  It is not showing continuity to ground at the joined end.

I'm using IN4004 diode.  What am I doing wrong?

Hmm is it possible i'm not using the volt meter the right way?

After the diode I cannot just simply check for continuity to ground anymore, right?

I think is this not backwards...  according to all the diagrams I've found you want to twist together the side with no stripe..

I really can't check for ground with my meter for some reason.

I even tryed just hooking up a diode (alone) to the probe, and the other ends never show continuity.  Flip it around it's the same..

I believe the meter just don't put enough current to measure properly??

However, I was able to put my probe to 12V and then the negative lead to the jointed connection of my diodes, and I was able to toggle 12V on and off with each door properly.

Learning alot today