I'm trying to install an aftermarket backup alert system in my 2005
Allure (LaCrosse). The system is supposed to be powered by tapping into
the backup light circuit. I'm pretty incompetent when it comes to
electrical circuits so I'm having a problem. If I look at the backup
light socket, it has two wires running into it...one black, one green.
I can't get a 12 volt reading when I connect a multimeter between the
two wires when the light is on.

What am I doing wrong? Am I using the correct wires? If so, which one is + and which is -? And why don't I get a 12v reading?

Any suggestions would be appreciated.

Brian

By trial & error I figured this out....black is ground, LIGHT green is pos.

Brian