Another SWR problem

Was there absolutely nothing running on the Jeep? What about lights? Do you have any LED lights? They can interfere with radio. Do you have an LED dome light or any others that would be on with the key off? LED brake lights and your foot was accidentally on the brake?
I have no LEDs, nothing on that I can remember
 
I have no LEDs, nothing on that I can remember

Hmm. I'm stumped without being able to look at it but something isn't right. You might be able to live with it but don't. When I first got into ham radio I bought a terrible radio and didn't know it was terrible until I got a new one. I just thought it was normal and I was really frustrated with radio because of it.

Three simple ideas to try. Unscrew the coax from the back of the radio and see if it still makes that sound. That will eliminate the coax and antenna. You could also leave the coax connected and unscrew the antenna to eliminate the antenna.

Second idea, take the radio out of the mounting bracket and see if it still makes that sound. If the bracket is screwed into metal, it is likely acting as a second ground point for the radio (depending on how the radio is made). That's fine and probably isn't a problem, but it's something else that can be eliminated as a potential problem.

Third idea, did you say your dad got a cb too? Can you put his in your Jeep and see if it works? That will tell you if it's your radio or your Jeep. You could also put your radio in his vehicle or trade coax and antennas if that'll help pin down the problem.
 
Second idea, take the radio out of the mounting bracket and see if it still makes that sound. If the bracket is screwed into metal, it is likely acting as a second ground point for the radio (depending on how the radio is made). That's fine and probably isn't a problem, but it's something else that can be eliminated as a potential problem.
FYI: The Unidens have an isolated chassis - or at least my 520xl does. If the above doesn't apply/work - try the opposite as well. Purposely ground the chassis. I also have a noise filter on the power leads.
 
And if I unplug the coax at the antenna but leave the other end plugged into the radio its only a small fuzz, does that mean my antenna is off somehow?
 
Three simple ideas to try.

One less simple idea that I meant to mention. It probably isn't the problem since the engine and everything else was off, but if you're under the hood might be worth trying. Unhook the ground wire from the battery and attach it to the ground point on the firewall behind the engine. This goes back to the second simple idea I mentioned. If the bracket goes into metal, the radio is probably grounded to the Jeep body at that point. Grounding to the battery creates a second ground path for the radio and it's the only direct line to the battery in the Jeep because everything else is also grounded to the body. All the power in the Jeep goes back to the battery, usually through the body to the firewall ground and then to the battery, but in some scenarios it will flow through the radio and use the radio's ground wire to the battery.
 
One less simple idea that I meant to mention. It probably isn't the problem since the engine and everything else was off, but if you're under the hood might be worth trying. Unhook the ground wire from the battery and attach it to the ground point on the firewall behind the engine. This goes back to the second simple idea I mentioned. If the bracket goes into metal, the radio is probably grounded to the Jeep body at that point. Grounding to the battery creates a second ground path for the radio and it's the only direct line to the battery in the Jeep because everything else is also grounded to the body. All the power in the Jeep goes back to the battery, usually through the body to the firewall ground and then to the battery, but in some scenarios it will flow through the radio and use the radio's ground wire to the battery.
If I leave everything like normal except remove the antenna, it is almost silent, just a slight buzz, does that mean somethings wrong with my antenna?