Purpose of shielded wire in backup camera wiring?

A

atikovi

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Apr 27, 2010
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Suburban Washington DC
Adding a factory navi radio and factory backup camera to a Nissan Versa. This model never had that option so it’s not pre-wired for that. Got the parts from the junkyard along with pigtails but will have to make a 4 wire harness from the trunk mounted camera to the radio. I see in the wiring diagram as well as on the radio pigtail that the black #1 CAMERA SHIELD and the green #2 CAMERA + wires are covered by a shield.

Versa bu cam wiring.jpg


What is the purpose of the shield and would I have to find such wire as well?

IMG_8504.JPG


IMG_8505.JPG
 
Pretty common on wide bandwidth unbalanced signals, like video being run over coax. If they had done something like twisted pair it might work, but may have worse problems with noise pickup. Anyhow. RF signals on coax (or twisted pair) are just like all other signals: you need two wires for it to work. But unlike low frequency signals, the other wire can't be the chassis, the return current has to be next to the "signal" wire, but its physical location is part of the circuit. How far apart the wires are impacts how the signal travels down the wire.

That looks like coax. The braid is way longer than I would ever tolerate, but it's not that fast of a signal... If you have any RG-174 lying around you could splice it in. Odds are, no matter how ugly it is, it will tolerate a few splices and work. There's perfect, and there's good enough. If it mattered you would see real RF connectors here.
 
Some shielded microphone cable would work well in this application. You need a 2 conductor product. Might be available at your local musical instrument store. Beldwin 5150 is the number I think.
 
I don't know what the purpose of the wire is, but the grounded shield on it is to reduce electromagnetic interference. Actually I would hope that most signal level wires, like for sensors, to be shielded if run in the same bundle with other wires, but hey I'm not the one designing these things.
 
I don't know this to be the case, but it could be that the shielding is to block outgoing interference from those wires if they carry power to run the camera.

I recently ran power (5V) through the A-pillar and headliner of my F-150 to run a dashcam mounted near my rear view mirror. Immediately afterwards, I lost almost all of my lock/unlock/start range using the key fob. I disconnected power to the dashcam wiring, and my key fob range was restored. I drew the conclusion that interference from the new wiring must have been affecting the key fob antenna in the truck.

It could be that non-shielded power cables routed near the signal-carrying cables from the camera would have a similar effect.
 
Might work, just use one pair. I would not use in high flex nor wet locations though, doesn’t strike me as rated for either.
 
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