wiring info needed for 2 backup cameras

I have a Kenwood DNX-7100 in a 06 Ford F350. I have 1 backup camera installed to trigger on the reverse. I'd like to add a second camera in the bed, with the ability to toggle between the 2. I'd like to keep the original triggered by reverse OR by the toggle switch. Not sure how to make it all work or if it's possible. Thanks.

hi, you'll need to make a simple video switcher..a bosch type relay will work fine. three phono plug/jack pigtails, depends on wiring on your cameras. a few 1N4001 or equiv diodes. you didn't state the switch you'd like to use. wire as follows: center conductor of rear camera to term 87A, center conductor of bed camera to term 87, center conductor of camera input of head unit to 30, connect all shields together, term 85 to ground, term 86 is + trigger in, cut the existing reverse trigger input lead, insert diode (banded end to head unit), connect another diode (banded end to head unit) on the same lead, +12 volts from your switch on the non banded end of this diode, along with term 86 of the relay, will send the video signal of the bed cam to the head unit. doesn't the DNX7100 have external switch functions?...ext sw? mark

I had been trying to wire it with switching the power, but your saying switch the video signal itself and the power. Got it. I have a 3 way dpdt rocker switch. Not sure on the specific though. Thanks a bunch

just switch the video signal, don't worry about the power...leave them both connected to accessory power. how exactly would you like the cameras to operate?... position 1-rear cam on manually, position 2-rear cam on in reverse, position 3-bed camera on manually?

That's exactly what I need. It's an On-Off-On switch.

you'll still use the relay to switch the video. center (common) term of switch to accessory power. one side to reverse trigger input of the radio. other side to the "+12 volt from your switch..." from my post above.

It essentially a DPDT relay with NC being the video & power to the front camera, and the NO for the rear camera. (Or use SPST if cameras to be powered all the time etc.) The grounded (85) relay's coil (86) is energised by the reverse switched +12V or the the manual switch - both going through any 1N400x diode with Kathodes (band end) at 86.