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I am installing a backup camera in my truck. I am getting some source of electrical "noise" in the electrical system in my truck and its not allowing the backup camera to operate. Let me explain a little further. (thanks for your patience)

  • Installed the head unit and backup camera in the truck, Head unit is pretty standard, it has a 12 volt (+) input to trigger the head unit to "see" that the truck is in reverse.
  • the camera is connected to the head unit via an RCA cable with an additional (+) and (-) line included.
  • at the camera end of the RCA line there is (+) and (-) tag ends hanging out that you are to connect to the reverse light harness on the truck.

Basically when you put the truck in reverse, the power is also tapped to the camera, when the camera is powered it sends a (+) signal to the head unit and it flips the screen over to the reverse camera automatically.

When the truck is off but key in the on position and I put the truck in reverse the camera works not a problem. When I start the truck and put in reverse the screen simply goes to the yellow ! on the screen. According to the manual they are saying its because there is interference with another signal. Im assuming at this point its with the alternator or something with the engine running.

In the installation manual they have a pic of a filtering circuit.

filter diagram out of installation manual

I believe that in the diagram has the polarity on the capacitor is incorrect? Should not the negative lead of the capacitor be on the negative lead of the 12 volt circuit?

In my local electronics store I could only get a 3300 uf cap but I believe this should be ok in this instance.

also to verify please the band on the diode should be toward the backup camera correct?

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Seeing as neither the diode or the capacitor is actually shown with a standard symbol, it's difficult to argue if it is drawn 'wrong'. However, for clarification, it should be like this:

schematic

simulate this circuit – Schematic created using CircuitLab

A 3300uF capacitor should be fine, but you could always get a smaller ceramic capacitor in parallel with it if you are unsure, they are cheap enough that it doesn't matter if you buy some and find they are not needed.

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The diode is shown correct in the diagram.Talking of polarized electrolytic capacitors these should never be connected in reverse polarity with power supply or tgey will pop or explode depending on the conditions.Now the thing is that in most of electrical schematic diagrams positive lead of cap is shown by a marker or line.Maybe they messed it up.Either they (manufacturers) have shown the negative pin of cap with line or it was just a mistake, who knows.The thing to remember is that positive pin of electrolytic capacitor goes to positive connection of supply and negative to negative of the supply. By the way you could also add an inductor in series with the camera after diode to further smooth out the voltage. Please let me know if adding filter solved the problem.

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  • \$\begingroup\$ Thank you, just wanted to verify what I was about to do first, going to try and install tonight, will post an update \$\endgroup\$ – Jason Harding Jan 30 at 13:26
  • \$\begingroup\$ We are in the middle of a cold snap here In ontario, should break tomorrow, will post an update when installed \$\endgroup\$ – Jason Harding Feb 1 at 13:48
  • \$\begingroup\$ Further update, I've installed the filter and the symptoms are the same. If I start the truck and immediately put it Into reverse the camera stays on for 5 seconds. And then goes to the yellow !. If I turn the key to "on" and put the truck in reverse it will say active forever. Is the filter design flawed? \$\endgroup\$ – Jason Harding Feb 2 at 17:55
  • \$\begingroup\$ No there is no flaw with filter design.Check the voltages. \$\endgroup\$ – Umer Feb 2 at 19:02
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So after much frustration and many hours working with atoto found out the problem. Bad rca cable from the stereo to the camera, specifically the end on the radio. Was working on it and had the deck sitting on the dash with the cable a little tight, suprise the camera stayed on. Started messing with the connections and got it to knock out by twisting the rca connection about 45 deg and 5 sec later out goes the camera feed. Thank you to everone who viewed and commented. Solution is stupid but still a solution.

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