Just finished installing my Mstudt cb radio mount along with my firestik antenna. When i went to just test it, my horn started going off.

Here is how everything is wired:

from battery to bluesea fuse box. From fuse box to the Cobra CB radio. From the radio the firestik cable going to the cb radio mount. Then the firestik antenna, from top to bottom: HD spring, mount adapter, split washer, metal washer, fiber washer, CB RADIO mount, cb radio cable, bolt.

Now, the horn goes off,on,off,on kinda like a alarm. Only when i press the push to talk button on the walkie. And only in the CB mode. If i press PA then the horn does not go off.

Is this normal? ( The cb radio is not tuned yet )

oooo, that's a fun one.

Try unplugging the antenna and see if it does the same thing. I doubt it's the antenna but that should rule it out if it keeps doing it.

Then I'd try a temporary power hook-up straight from the battery, with a fuse, ideally.

Then go back to your old hook-up, but move it off the blue sea to the battery. And so on. Eventually, you'll narrow it down.

Do you HAVE an alarm, or WAS there one? Certainly the first suspect.

I don't know if it's the same for CB radios or not but for ham radios it's extremely bad to hit the transmit ( or talk ) button without the antenna attached . Something to keep in mind while trouble shooting . Good luck .

lol this is funny isnt it. Antenna is brand new, cobra cb radio is used.

I will try removing the antenna and see if it does this.

I have a 5amp fuse installed in the bluesea, thus powering the cb radio. ( Theoretically this should not affect anything, but i will try straight to battery)

I do have an alarm. The stock oem alarn VIP RS3000. It is in "valet" mode. On top of that i have a aftermarket viper alarm wired. ( I cannot remove the stock oem alarm because the car wont start, meaning it is hard wired deeply within the oem harness) But like i said, it is in valet mode, basically disabling everything but still lets you start the car. The horn works of ground relay.

Seems like RF getting into the horn. Running more than 4w?


Sent from my iPhone using Tapatalk

im sorry, what?

I have a theory. Is the on-off horn thing like the panic mode on your key fob? The receiving antenna for the fob is like a foot from that antenna.

I don't think there is anyway a CB RF signal could POWER a horn, but it might TRIGGER it.


EDIT; The above about the antenna is true for '99+. I don't know how the '97 is set up, let alone the add-ons. But my test will give us something to go on.

RF = Radio Frequency = energy radiated when you transmit.

The Durk could be onto something.


Sent from my iPhone using Tapatalk

So I'll try what Durk said in the first reply. And get back to you all tomorrow after

Actually, it's a pretty simple plug-n-play installation/removal. It taps into the harness right under your ignition- right at the base of your steering column "clam-shell". You can un-plug the alarm connectors that are sandwiched between your dash harness and ignition harness, and plug it back in without the alarm harness. Could probably be fully removed in 30 minutes tops.
Might help narrow down your issue. At least it would take a possible cause out of the equation.

I looked at the harness , to me it did not look simple. And unplugging the brains does not allow you to start the truck. Have you actually done this ?

I don't see why a alarm would cause a issue with using a CB radio. 99% of people here have a stock alarm and use cb radio

I'm wondering. If a untuned antenna can cause this ? Also I should mention that the aftermarket alarm horn wire runs in the same batch of wires that the cb power wire runs. Meaning out of the firewall they all run together. Then the horn wire continues to the horn. Where it is t-taped in. Because I did not want that ugly bulky speaker that the aftermarket alarms come with.

would this theory apply if, i am running a wire from the aftermarket alarm brains to the oem horn. And the power wire for the CB radio is right there also ? its raining today ): can't do much testing GRRRRR

No. I just don't see how the power wire can have that kind of effect. Just DC current used by the radio can't do much of anything unless it shorts directly to the horn. But that's not it,because the power cable is active whether it's PA or CB. I have never heard of RF (radio frequency--the funky high-frequency stuff going to the antenna) feeding back up the power cable so as to do anything spurious that way. Anyway, if disconnecting the antenna stops the problem, that rules out the power cable concept.

What I would really like to know is if the horn blowing is being triggered by the alarm system. So it would be really cool if you could either disable the alarm or divorce it from connection to the horn. Both alarms, actually.

I don't believe there is anyway a CB radio can make a horn blow without having an alarm circuit in the middle. Still, electricity is always full of surprises.

so i took the antenna of and it tested it. It still made the horn go off. Then i took out the fuse form the bluesea aux fuse box for the CB radio, then put it back it. Went to test it with the antenna installed. No horn going off.

Could pulling the fuse and installing it back have fixed the horn issue? And to truly know if your cb radio is picking up properly, it must be tuned ?

so long story short, after pulling the fuse and putting it back in. The horn is silent and no longer going off, in "cb" mode or ""pa" mode.