NOT PLC related just looking for ideas

Good morning all, this is not PLC related so if not allowed just delete. But i have a problem with my RV that has got me stumped big time. I have asked many friend and family and they are also stumped. So i am hoping to ask on here and see what information i can obtain.


So i have a fuse distribution box that feeds various items in the RV. I have a schematic for said system. There are two 12v feeds. Each comes from a 5a fuse. I am in the process of installing a back up camera. I know fuse 1 goes to 1 vent fan and 3 lights against the left side of RV and fuse 2 goes to 1 vent fan and 3 light on the right side.


So if i hook my camera up to the power on the left side, although i get 12v at all times, measured with a meter, and the indicator on the camera says everything is powered, i do not get a signal from camera to display.


But if i hook up the camera to the right side, i still get 12v, still get the same amp draw, everything looks the same as far as i can tell, but hooked up over here on this side the camera and everything works good.


So i thought ok maybe it might be a power or ground issue, so used right side power and left side ground, Nope does not work, used right side ground and left side power, nope does not work. This has got me totally confused being as draws the same power and same amps on either side but will only work if connected to right side. Yet everything on both circuits works great, fans, lights, everything. I even tried using the shell of the RV as ground, again if connected to the left side nothing, connect to right side works fine.


Just running out of ideas as to why this is. I know i could just keep it on the right side but it looks much better and neater if connected to left side.


Thanks for any feedback you can provide or think of. Ive even had a friend of mine who works on RVs look at it and he is stumped.

Did you check the polarity of the 12V?

It might be a center tapped 24V system and the one fuse to ground gives -12V. The camera might "power up" with reverse polarity but not work correctly.

Check for voltage between fuse 1 & fuse 2 and see if they show 0V, 12V or 24V.

It kind of sounds like they are using a distribution box with a "neutral" bar and a "ground bar" and they are not connected together.With power off, what is the resistance between the two grounds? Do you have a model number and manufacturer for the distribution panel?

First let me say RV's don't have 24V systems they are all 12V Neg ground
i have seen large diesel truck use 24V start 12V systems

i have hooked up a few back up camera's and i usually hook them up to the backup light power.
newer vehicles have the right and left light split this 2 fuss
an RV would also have a separate fuses for the trailer plug
post or PM a copy of the schematic and may we can offer better help

Back in the olden days when I was a skinny teenager, I spent many hours upside down under the dash of vehicles installing audio equipment and got pretty good at it. In that era, ignition noise was the bane of quality hi-fi and the location and quality of the ground could make all the difference. I did not have a multimeter, so there was a lot of trial an error and a handful of choices for noise filters that we would resort to so we could eliminate alternator whine and ignition buzzing from the white space between in our loud metal music blasting through the best 6 x 9s every produced, the Pioneer TS6907.

I don't know if noise could wipe out a video signal, but it would be on my list of suspects. If the thing won't work with everything else off (engine, fans, etc.) then the cause is probably something else.

I have a camper. The back up camera is powered by the trucks 7 wire connector to the camper. The back up camera is on when the head lights are on.

That's strange the 7 way plug doesn't have the headlights
Marker Lights
Right Turn
Left turn
12V Power
Ground
Break Power
Backup Light
i normally hook them to the Backup Light terminal
i think it's the center terminal i would have to look it up

What little experiences I have had with RV wiring, boats, and one fiberglass car, the grounding is often done with wires connecting various metal parts together through the chassis. I'd suspect the root cause will end up being a "high resistance" (barely existent) ground that is good enough to light an LED and show potential on a multimeter, but not good enough for the camera to produce a video signal correctly.

OkiePC said:

What little experiences I have had with RV wiring, boats, and one fiberglass car, the grounding is often done with wires connecting various metal parts together through the chassis. I'd suspect the root cause will end up being a "high resistance" (barely existent) ground that is good enough to light an LED and show potential on a multimeter, but not good enough for the camera to produce a video signal correctly.

Click to expand...

same experience with wiring trailer lights: it's almost always the ground.

GaryS said:

That's strange the 7 way plug doesn't have the headlights
Marker Lights
Right Turn
Left turn
12V Power
Ground
Break Power
Backup Light
i normally hook them to the Backup Light terminal
i think it's the center terminal i would have to look it up

Click to expand...

If you connect the 12V Power wire to a headlight wire under the hood there is.


Or


He tied into the Marker Lights wire and they come on with the headlights (and parking lights but whoever tests their parking lights when they get out of the vehicle?)

run a temporary ground wire to the battery neg terminal to see if the problem persists to rule out grounding issues - remember this is just a insulated wire thrown over or under the vehicle for testing

GaryS said:

That's strange the 7 way plug doesn't have the headlights
Marker Lights
Right Turn
Left turn
12V Power
Ground
Break Power
Backup Light
i normally hook them to the Backup Light terminal
i think it's the center terminal i would have to look it up

Click to expand...

Don't the tail light come on when the head lights are on? It may be connected to the tail lights but they come on when I turn on my head lights.

Peter Nachtwey said:

Don't the tail light come on when the head lights are on? It may be connected to the tail lights but they come on when I turn on my head lights.

Click to expand...

Another thought:


That's if you read the instruction manual and don't just hook up the vehicle connections where you want to when adding the trailer wiring connector.


And in this field how many of us read those manuals the first, or second, try.