Help w/ my CB wiring

After doing quite a bit of research on how to wire a CB (aparently not enough at this point), I got it wired to my Jeep, but the CB wont' turn on. I know it's best to run it directly off the battery, but I didn't want to do that - I figured this would be a good option as I'm not a heavy CB user and I can live with some engine noise.

Here's what I did:
For the positive connection I soldered a fuse tap (http://shop.advanceautoparts.com/we...-10-Amps-Bussmann_5080114-P_N4017D_A|GRP2020A) to the end of the positive wire and connected it to the junction box (the box that is next to the passenger's right foot) into fuse 18 (10 amps and appears to be the power mirror switch from the FSM). I did it this way so that I can use it with either the Jeep on or on ACC - I don't want constant power to it.

For the negative connection, I soldered a ring terminal (I used the extra wire that I bought for the positive connection - I don't think that could be the problem; 14 ga is 14 ga, right?) to the end of it and fed it up under the knee blocker (right under the steering column) and screwed it directly to the single screw (in front of the driver's right knee) that is screwed into the the large metal piece directly behind the knee blocker.

Did I wire this incorrectly? Did I maybe blow the CB? I tried different fuse locations but still have the same result. I know the CB worked before I did this and now it will not power on with the Jeep running or in ACC.

BTW - I have a 2000 Sport, 4.0L and used 14 gauge wire for my wiring.

Thanks so much!

What make/model of CB? Might sound stupid... But is there a fuse on the back side of the CB? I wired mine the same way essentially. Power from fuse block w/ inline fuse, ground on fire wall. Done.
Check to make sure you have a GOOD ground. Bare metal is ideal. Maybe check CB directly from battery too.

It's a Cobra 75wxst and it appears to have an in line fuse on the positive wire. Its tubular shape but I can't open it to verify that it is in fact a fuse.
I bought it off Craigslist a few days ago and the guy I bought it from showed me that it does work.
I have the ground wire on bare metal - unless what I think is bare metal is maybe aluminum. It's the metal piece directly behind the plastics knee blocker under the steering column.

Stupid question:

Did you put a fuse in the Fuse extension you installed?
Is the in-line fuse good on the CB?

Did you check the operation of the CB before trying to install it?

Use a Volt meter ($4.99 HF) to check for voltage between ground and where you tapped in.

CB's are usually insanely easy to hook up. If nothing else, use a cigarette lighter plug and solder it to the CB power leads to get it going, then figure out which circuit you want to use on the fuse block. Use Volt Meter to see if it is actually active.

Hope that helps.

Edit: That metal brace may not actually be grounded. Ohm it to the chassis (Sill screws work OK for that purpose, or even the fuse block mounting screws).

I have the same model. I wired mine into the drivers compartment overhead light leads.
As stated by above poster check your inline fuse, iirc it is very low voltage And very touchy.

amorth said:

It's a Cobra 75wxst and it appears to have an in line fuse on the positive wire. Its tubular shape but I can't open it to verify that it is in fact a fuse.
I bought it off Craigslist a few days ago and the guy I bought it from showed me that it does work.
I have the ground wire on bare metal - unless what I think is bare metal is maybe aluminum. It's the metal piece directly behind the plastics knee blocker under the steering column.

Click to expand...

Def use a volt meter between your +/- connections, Place a magnet on the spot you connected your ground. I'm not sure if there was any alum behind there. Disconnect from both ends and check continuity between +/-

Or disconnect and re connect directly to battery

WB9YZU said:

Stupid question:


That metal brace may not actually be grounded.

Click to expand...

/\This too

Thanks for the ideas everyone. Tomorrow I will take it out and hook it up to the battery to test it again. I'll try to somehow disconnect what I think is the in-line fuse (this is what it looks like but only white - http://www.radioshack.com/product/index.jsp?productId=2102786) to see if the fuse is blown. Maybe replace the entire thing?
I'm not sure how to use a voltmeter, but now is as good of a time as any to figure it out.

WB9YZU said:

That metal brace may not actually be grounded. Ohm it to the chassis (Sill screws work OK for that purpose, or even the fuse block mounting screws).

Click to expand...

I think you'll find that this is the problem. To confirm this take a 3 ft piece of wire and strip both ends back a half inch. Put one end of the stripped wire under your current ground location and secure it. Take the other end and touch it to the bare metal drivers door pin or any bare screw on the door. If you power the CB on, you should see it turn on.

If you look up under the dash on the right had side of the steering column, you'll see a huge bare hunk of unpainted metal that looks like aluminum. As a recall, there is a hole already drilled in this piece up towards the top right hand side. Use a 1/4 inch bolt about 3/4 inch long with a nut and washer and secure the ground eye there.

One thing that didnt get mentioned yet, if it still isnt working yet. Make sure you have the atennea completely hooked up correctly, if for some reason you do not and try to key that mic that will blow the cb as well. I found this out the hard way one day. I know it sounds dumb but alot of people do this and didnt even realize it untill its to late. good luck man.

My Cobra won't power on unless the mic is hooked up. This may be worth checking since it's pretty simple to eliminate.

This is the easiest thing you can possibly do to a vehicle
It's 2 wires. A hot fused wire & a ground.

You don't hook the CB directly to the battery.

You stick the hot wire into the fuse box, into a slot that turns on/off with the turning of the key.
That way the CB is disabled & not pulling battery power when the vehicle is turned off.

And you attach the ground under the dash somewhere.

How can this be confusing?

barillms said:

This is the easiest thing you can possibly do to a vehicle How can this be confusing?

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Somethings easy to you may not be easy to him, and vise versa. I was once told... The only stupid question, is a question never asked. We're all here to help. Now that my friend.... is pretty simple. :cheers:

CaliXJ said:

Somethings easy to you may not be easy to him, and vise versa. I was once told... The only stupid question, is a question never asked. We're all here to help. Now that my friend.... is pretty simple. :cheers:

Click to expand...

Exactly that!

You don't hook the CB directly to the battery.
You stick the hot wire into the fuse box, into a slot that turns on/off with the turning of the key.
That way the CB is disabled & not pulling battery power when the vehicle is turned off. And you attach the ground under the dash somewhere.

Click to expand...

And you can install a transceiver that way if you have to but thats not the preferred way to wire it. Hooking it up that way is a gamble as to if your circuit has enough power to properly feed the transceiver and it also greatly increases your chances of creating ground loops. This can manifest itself as induced hum / hash noise on receive AND transmit and can also cause interference inside the vehicle to other components like the stereo, or in severe cases interfere with the PCM itself. There are times that installing a communications device this way may be the only practical way to do so, but its by no means the preferred way.

Explain a ground loop on a vehicle please...

maybe my electronics/engineering degree havent taught me anything at all... or are you talking about impedance in which case... still wrong

Tacedaddy said:

Explain a ground loop on a vehicle please...

maybe my electronics/engineering degree havent taught me anything at all... or are you talking about impedance in which case... still wrong

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By ground loops he probably means a "short." That's what we called it when i was in class. Strange, yes. ::shrug::And while we have no trouble with wiring/electronics, it's not for everyone.

To the OP, double check all your connections are tight. Make sure that have the hand unit screwed SNUGLY and connected to the control box. You could try grounding the box itself too. But make sure that you have an antenna connected before you key it; then tune said antenna.

Tacedaddy said:

Explain a ground loop on a vehicle please...

maybe my electronics/engineering degree havent taught me anything at all... or are you talking about impedance in which case... still wrong

Click to expand...

Congratulations on your electronics degree. That means you implicitly understand that an electrical ground for a device (in this case a communications transceiver) can be incorrectly installed such that a voltage potential exists on the ground circuit when referenced back to the battery. This very oversimplified explanation is often referred to as a "ground loop" and most often occurs when the device is not hooked up directly to the voltage source, in this case, the vehicle battery.

Your electronics degree should also have taught you you to recognize that this unwanted voltage potential can be and often is responsible for noise in various systems but can also be responsible for objectionable noise on received and transmitted audio signals and is the reason that communications equipment manufacturers recommend direct connections to the battery.

Would you now like to discuss how "ground loops" can induce noise on sensitive logic circuits for the PLL of the transceiver or would you prefer the discussion move towards incorrect antenna installations and how subsequent mimatched antenna feed and feedline impedances give resultant high SWR which can devistate automotive sensor signals and computer function during transmit?

Well, I finally got it figured it out :clap: I had everything setup correctly, I just didn't install the 10 amp fuse that I'm using back into the add-a-circuit. Apparently, that is needed.

On a scale of 1-10 on electrical knowledge, I sit at about 1.5 - so for those of you out there that are trying to wire your CB to the junction box (yes, connecting to the battery is the best way - I chose this way because it was easier and is a clean install) in the passenger foot-well, here's whatcha need to do:

I have an all-in-one hand held unit - a Cobra 75wxst - here's how I did it.

Buy these:
Bussman ATM Fuse Tap - 10 Amps (#BP/HHH);
Roll of 14 gauge wire (I bought red);
Ring terminal for 14-16 gauge wire (I used Dorman #85408);
Heat shrink tubing.

Do this:
1. Solder a good length of 14 gauge wire (or however much you think you may need) to the positive cable coming off the CB and then cover the connection with some heat shrink tubing. **If there isn't a fuse anywhere on this wire, you really should add one. Just get an in-line fuse holder and add a 10 amp fuse (probably overkill, but hey, why not), solder it up and your good to go.**

2. Crimp the fuse tap (sometimes called add-a-circuit) to the other end of the wire you just added and then cover the connection with some heat shrink tubing.

3. Solder a good length of 14 gauge wire (or however much you think you may need) to the negative coming off the CB and then cover the connection with some heat shrink tubing. **Instead of buying an additional roll of black wire, I just used the red and wrapped some black electrical tape around a few spots of the wire to indicate it was negative.**

4. Crimp a ring terminal to the other end of the wire you just added and then cover the connection with some heat shrink tubing.
Your wiring is complete!

Install:
Now this can be done in multiple ways, so figure out how you want these wires laid out in your Jeep. Here's what I did......

First I decided I wanted to mount the connector box somewhere under the drivers seat (I may change this later but with how I laid this out, it will be an easy adjustment). I then routed the positive and negative wires up under the center console towards the dash. I then removed the knee blocker from under the steering column. There is one screw (possibly more, but mine only had one) to the right of the column - this is where I mounted my ring terminal (ground). With the knee blocker installed, this provides a nice way to hide the negative cable. :thumbup:

Finally, I routed the positive cable (fuse tap) behind the center part of the dash toward the junction box. I used the 10 amp fuse from slot #18 (this provides power to the CB while the Jeep is on or in "acc" mode) and installed it into the fuse tap then connected the fuse tap into slot 18.

That's it - my CB now has power! 10-4 good buddy!

This may be a weak write-up but I figured I should stop lurking and try to contribute something to this fantastic forum!! Hopefully someone out there will find this useful. :cheers:

Thanks for your responses everyone!

Glad you got it figured out man!! Time to get out on the trail and use it now.

amorth said:

After doing quite a bit of research on how to wire a CB (aparently not enough at this point), I got it wired to my Jeep, but the CB wont' turn on. I know it's best to run it directly off the battery, but I didn't want to do that - I figured this would be a good option as I'm not a heavy CB user and I can live with some engine noise.

Here's what I did:
For the positive connection I soldered a fuse tap (http://shop.advanceautoparts.com/we...-10-Amps-Bussmann_5080114-P_N4017D_A|GRP2020A) to the end of the positive wire and connected it to the junction box (the box that is next to the passenger's right foot) into fuse 18 (10 amps and appears to be the power mirror switch from the FSM). I did it this way so that I can use it with either the Jeep on or on ACC - I don't want constant power to it.

For the negative connection, I soldered a ring terminal (I used the extra wire that I bought for the positive connection - I don't think that could be the problem; 14 ga is 14 ga, right?) to the end of it and fed it up under the knee blocker (right under the steering column) and screwed it directly to the single screw (in front of the driver's right knee) that is screwed into the the large metal piece directly behind the knee blocker.

Did I wire this incorrectly? Did I maybe blow the CB? I tried different fuse locations but still have the same result. I know the CB worked before I did this and now it will not power on with the Jeep running or in ACC.

BTW - I have a 2000 Sport, 4.0L and used 14 gauge wire for my wiring.

Thanks so much!

Click to expand...

Sounds like a nice setup wish i thought of that but what i did was i tapped into my after market radios power and ground connections soldered it together and capped wires it works great for me. my cb is mounted to the right of the shifter and i was able to conceal the wires behind that dashboard cover that pops off.