Hi all, it's been a while since I last posted but I run into a problem that I need to solve for She Who Must Be Obeyed. I've installed some rear view cameras on our horse trailer and those connect to our truck with a small waterproof pigtrail. There is a single camera mounted on the truck tailgate to aid in hitching up, and one on the back of the trailer as a rearview when trailering, and one inside the trailer so she can keep an eye on her dearly beloved.
The camera monitor normally displays a split screen view of the interior and rear view from the trailer when the trailer is connected. It also has "sense" wires that can be connected to 12V to force the monitor to display a particular camera. I currently have one of these wires connected to the truck backup lights which cause the hitch camera to display when the truck is put in reverse and that is perfect for hitching up. Once 12V is removed from the sense wire, the monitor reverts to the normal split screen view.
Here is the issue - SWMBO would like the trailer rearview camera to be displayed whenever the trailer is connected, and the truck is in reverse. So, I somehow need to sense when the trailer rearview camera is drawing power (100ma normally up to 500ma at night [IR LEDs automatically come on in low light]), and actuate a 12V SPDT relay to switch between the two different "sense" wires and the backup light switched 12V source. I have a small 12V automotive relay I can use for the switching with a coil resistance of 222ohms and a nominal operating current of 53ma, but it would be nice to have a solid state solution however I was unable to locate any double throw solidstate relays.
As always, your help is greatly appreciated.