Reverse sense wire....where is it?

[jbourassa]

Alright I did the test and it's the same thing on the passenger's side, still switched from the ground. I'm not too familiar with circuit but I was wondering if a relay could help sense ground and output the +12 volt I need at the right moment?

Ok I went to my local CanadianTire and buyed a car relay switch, the thing worked like a charm. My monitor finaly get triggered only when I go in reverse. If someone needs to use a relay like me the way to hook it is to have the positive backup light wire connect to both 85 and 30 terminal of the relay and the ground of the backup light to to 86 terminal of the relay after that hook your remote trigger wire to the 87 terminal of the relay switch. that way there only a +12 volt on the 87 terminal when the circuit get closed going through the 85 to 86 terminal which trigger a switch between the 30 and 87 terminal. Hope this helps someone.