Gregg said:
Sorry may have over simplified since the original post was pertaining to a Rear View Safety product that utilizes a Multiplexer. That is the system that I have installed. Checked out the web site for your product and you are right, rather confusing but believe you are correct in the camera for your product actually gets it feed from the reverse lights. Did not immediately appear that way when looking at the wiring harness you posted. In this situation, you will unfortunately need to add a switch. If you want the dual option, more importantly you will also need to add diodes to prevent the backup lights from coming on when you flip the switch during normal travel viewing. Could be rather startling to the drivers behind you. The diodes will isolate the reverse lights and prevent that from happening. Here is a link to a YouTube video to better understand what happens and what is needed. https://www.youtube.com/watch?v=kUpD5WzySTI
Hope that helps. I will check tomorrow to see if I still have the diodes that I purchased and did not end up needing. If so, I can send them to you. Fellow Ohioans need to help each other out.
I did not start my install this weekend. Hopefully next. I will not have to have diodes. The diode solution is another good example of a video that gets straight into the details without spending a lot of time explaining what the overall situation is. Diodes are needed when one wants wire the back-up camera to the reverse lights and constant 12v at the same time. Under that set-up when one introduces 12v to the camera from the switch the reverse lights will light unless one uses diodes to isolate the reverse lights from that 12v. In my planned installation I will not connect the camera to the reverse lights. Also, if I install a switch it will be to turn off the 12v that would otherwise be on all of the time. It does have me thinking about that installation however because of these differences (I added info for folks that find this thread down the road). Here are 3 typical installations when using a camera that is wired without an additional trigger wire (typical) and a monitor that does have an additional trigger wire (typical).
A. Camera is wired to only the reverse lights. Diodes are not required. The monitor is wired to both the 12v constant and the reverse for trigger.
1) Camera comes on when in reverse and is off otherwise.
2) Monitor comes on when in reverse and goes off otherwise. Monitor can also be turned on at the monitor.
B. Camera is wired to only 12v constant. Diodes are not required. The monitor is wired to both the 12v constant and the reverse for trigger.
1) Camera is on all of the time.
2) An optional switch can be installed to turn off the camera but then it is off, it will not come on when selecting reverse.
3) Monitor comes on when in reverse and goes off otherwise. Monitor can also be turned on at the monitor.
C. Camera is wired to reverse lights and 12v constant. Diodes are required to allow the 12v constant to flow only to the camera.
1) Camera comes on when in reverse and is off otherwise.
2) A switch is used to also turn on the camera using the 12v constant for on demand viewing of the camera.
3) Monitor comes on when in reverse and goes off otherwise. Monitor can also be turned on at the monitor.
For installation "C" it is interesting to note that monitor will not automatically trigger when the camera is turned on via the 12v switch unless one also wires the camera trigger to both the reverse lights AND the 12v switch in which case 2 sets of 2 diodes are needed. Without this additional step one will need to turn on the camera and turn on the monitor to view the camera.
I am still leaning towards set-up "B" with the downside that if have left the switch in the off position my camera will not come on when I select reverse. My monitor still will and I'll just have to flip a switch to turn on the camera. I can also turn on or off both the camera and monitor at any other time in order to view the camera.
Thomas