How to wire a manual switch for backup camera

Thanks for all the helpful advice for wiring a manual override switch for my backup camera. Here is an update to this project, along with some photos.

After receiving the fancy illuminated SPDT latching switch I ordered on eBay, and considering the wiring advice graciously rendered on the rv.net forum, I jumped lustfully headlong into installation but probably should have spent more time testing before drilling the dashboard switch hole.

After wiring the SPDT switch as shown by SPDT Wiring, the backup camera will still displays its image on the LED display (like this) just as it did before adding the switch, but when the switch is placed in the override position, the head unit switches to the camera input but no image is displayed (like this). Which leads me to conclude that the camera is not being powered by the reverse signal from the gearshift, but is probably getting its power from the backup lights as some of you have suggested.

I was hoping that by feeding +12V to the camera from the ignition key signal, I could turn the camera on. But apparently this is not the case and I have no idea where in the motorhome wiring the backup light voltage is jumpered into the camera.

There is also a slim possibility that I need to connect the grounded cable shields where I inserted a weatherproof trailer light connector for the camera, but I'll have to wait until our new snow melts to test this out.

So while the lighted switch looks really cool, to see the camera output I still need to put the gearshift in reverse, which is inadvisable at highway speeds.

Any further ideas and suggestions would be appreciated. Thanks.

My RV is a 2004 Trail Lite B+ 235s and I think the original Voyager B/W backup camera was added by one of the previous owners. I got tired of hitting my head on the overhead monitor and when I upgraded the in-dash stereo I removed the monitor and fed the backup camera's video feed into the Xovision XOD1760BT standard camera input.

Although I cut the short section of exposed cable at the camera end to put in a weatherproof plug, I'm not sure how/where the camera is getting its +12v power. It might very well be from the backup light circuit, but this section of the camera cable is not exposed.

Unfortunately, the Xovision XOD1760BT does not have a menu option to display the camera feed, only the AUX video feed, and running the camera video into the AUX video input will bypass the reverse-signal backup logic which currently works.

Thanks for the heads-up on possible transmission/computer complications of backfeeding the reverse_signal line. I had not considered that.

Also thanks for the SPDT suggestion. For my situation I guess the wiring would be:

COMMON-Head Unit
UP (Auto): Reverse_Signal
DOWN (Manual): +12v

I may also look for an illuminated switch as a reminder that the camera is in manual mode.

Wire it to the running lights.

Is there a menu option on your head unit to display the camera? My Sony has that option. what I did is connect the reverse signal wire to a 12v source controlled by the ignition. When I want to view the camera I select it from the menu. I can easily switch between camera, GPS, and music source.

For the head unit, an SPST switch to the run circuit would work only if you also remove the wire from the reverse circuit on the chassis; otherwise, you'd be back-feeding the reverse circuit as well as turning on the camera display, which at the least would probably turn on the reverse lights when not backing up but might also cause the transmission or its computer difficulties. An SPDT switch would allow you to select between the current mode and always on.

bgum (and I in my previous post) allude to the camera's wiring, separate from the control signal to the head unit. It's not uncommon for the camera's power to be wired into the reverse light circuit, in which case activating the head unit when you aren't in reverse will switch its display to the camera input, but there will be no signal there to display when you aren't in reverse. Switching the power source for the camera to something else (like the tail light circuit) is the solution if that's the case.

Remove hot wire from backup hot wire and move it to tail light wire. It should then work when your tail lights are on. I just wonder if you have it wired to both will it activate with either reverse or tail lights.

Some systems don't wire to reverse signal but to backup lights. They get power from hot and ground in the clear backup lights. Or from running lights hot and ground. I have installed 5 or 6 backup cameras and always wires to reverse lights.

Thanks for the advice, DrewE and bukhrn. Here's a little more info:

Metering the Reverse_Signal wire from the vehicle into the Xovision head unit, I find that when the ignition is ON and the gearshift is in REVERSE, there is +12V battery applied in the Reverse_Signal circuit (relative to chassis ground).

I guess that means an SPST switch from Ignition to Reverse_Signal would power on the backup camera as long as Ignition was ON? However, I'm not sure if this would automatically turn on the head unit if the Xovision was switched OFF.

Decisions, decisions.

Typically I believe they're +12V signals.

If you use a SPDT switch for the wire, with the common going to the head unit and one contact going to the existing circuit, you can connect the other to +12V and see if it works. If for some reason it doesn't, just reconnect the new switch lead to ground instead...or try ground first and change to +12V if that doesn't work.

Hopefully, the camera itself isn't powered only when the reverse lights are on....

You could run it to the hot side of the ignition so it's on whenever the ignition is on, like mine or many others, it's nice to see what the toad is doing back there, not just for backing up.