Join Date: Jul 2012
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So to be clear, you only have the problem when you back up? You don't have it when braking, driving, or running anything else in the truck? If you simply disconnect the backup lights for a few minutes and back up, does the problem go away?
Ninety percent of the problem is finding the source, so if that's the case, you are well on the way. You can get rid of it and there are several combined approaches you can use. You want to know whether it's a radiated noise (comes down the antenna), a conducted noise (comes through the power lines and any grounding for the CB to the truck frame), or induced noise (an inductive effect in components of the radio because they are affected directly by electrical fields created by something else in the truck). I'm guessing you'll need some coaxial bypass capacitors inline with your low voltage wiring to the CB. This is also a pretty safe mod to do. To test it, use a power source other than the truck to run your CB -- borrow a battery or go to a shop that can connect a 12-volt supply to the CB. You'll also want to be sure that you disconnect all grounds to the CB and its antenna and connect them to a different ground. Using another truck is an easy way to do all this -- use the other truck to provide power and ground. If this did it, then go to your electronics shop and have them install the coaxial bypass capacitors. They are cheap and only take a few minutes to do.
If you have problems with radiated noise, you should be causing problems in a CB in a truck next to you. That's easily checked. If inductive noise, the problem is a bit more difficult and may just require a different CB unit or some shielding for it, or you may have inadequate cables or connections. I wouldn't rule this out, since this problem just started happening, which could suggest you have a broken cable or connection somewhere.
A couple inexpensive test instruments can really help you along with all of this, but you need to know how to use them too. If you don't, I'd talk to the shop you got your CB from, or a CB service shop.
However, and this is important, you can take actions to isolate your radio (the bypass capacitors or shielding it) without a problem, but doing anything that changes your ignition system should be checked with a specialist who knows your truck. With modern ignition systems, you can alter or damage the ignition system and cause all kinds of (unwarrantied) damage to your truck.