“Installing a Trunk or Remote mount two-way radio”
There are many different ways that radio installers/ technicians go about installing their systems, this is the way I have been installing commercial two-way radios for over the last 40 years, and it works for me.
There are several reasons why you may find yourself looking at a remote or trunk mount radio for your vehicle.
In my case I already had the radio and have used it for many years, so I was happy with the performance of an older commercial radio.
The main reason I decided on a trunk mount radio was that the interior of my new car didn’t really have any dash space to mount a dash mount radio or a control head.
These instructions will apply to almost any type or model vehicle with a little modification to the steps for your particular vehicle installation locations desired.
This is most important…make sure of what is behind where ever you plan to drill a hole or drive a sheet metal screw into any metal, especially under the carpet where vehicle wiring could be laying.
TIP – prior to installation, it’s a good idea to connect all the cables, microphone, speaker and power leads and verify that all functions of the radio are working correctly before mounting.
This installation will consist of the following steps:
- Removing the rear and front seat ( one side only) of the vehicle.
- Prying up on the bottom door molding ( front and passenger rear door ), accessing the carpet.
- Establishing the path I will use to run my cables from the rear trunk area to the front seat area and also to the engine compartment thru the firewall.
- Attaching the power supply lead securely and safely in the engine compartment.
- Mounting the transmitter/receiver package.
- Mounting the antenna system.
Removing the seats ( one side only in the front) of the vehicle and the entire rear bench seat.
The passenger front seat was bolted down with a large sized bolt, in this case it was a 19mm (3/4″ bolt).
Be careful when lifting the seat up, so as not to damage the wiring to the seat. Unplug the connectors under the seat, remove the seat and set aside.
In the above photo you can see the radio control cable is being brought out from under the carpet at a slit I made in the carpet to keep the cable away from the seat rear mounting bracket.
The black cable next to the air vents are the connectors to the seat motors. As you can see the carpet is molded and is tight to the chassis.
Here we have mounted the end of the cable which is how the Hand Held Control Head Microphone connects to the cable.
The smaller cable is how the Ignition sense power lead and the speaker cable is connected to the system cable and then routed under the carpet over to the side of the passenger kick panel.
Back seat removal
Removal of the rear bench seat consisted of lifting the front part of the seat until the two latches (one on each side) popped out of the holder in the chassis. (barely visible in the hole at the bottom of the photo).
Lift the seat bottom up and out, place out of the way.
At the bottom of the back part of the seat will be two bolts holding the back seat in place, remove them to loosen the back, giving you access to the trunk area to run your cables into. You do not need to remove the rear back part of the seat completely.
Above you can see that the control cable is coming out from under the carpet near the drive line hump in the floorboard. The large red power lead to the radio is following along the side of the floor next to vehicle wiring from the front close to the door edge.
Mounting the radio package in the trunk
I removed the side carpet covering in the trunk ( right side) to give me access to the metal brackets behind the rear seat.
This is where I will clean the paint away, wire wheel on my drill) exposing bare metal and bolt the radio ground lead using nut, bolt and lock washer.
Using 1/4″ hardware the mounting tray of the radio is mounted in three mounting hole locations on the tray the radio slides and locks into.
I elected to vertically mount the radio instead of flat on the floor, to keep the trunk area flat to accommodate a molded rubber Weather-Tech liner. The mounting tray is bolted to a bracket that is offset from the back of the trunk wall. This gave me room behind the radio to stowaway the remaining cable.
Due to the sunroof on this car, my usual roof mount antenna location had to go to the trunk lid.
After putting the trunk lid cover back on, the coax can be Ty-rapped to the trunk lid hinge arm. Make sure that you leave slack with the lid open but not in the way of any moving parts of the trunk lid.
The following is an NMO antenna mount. It requires a 3/4″ hole in the vehicle roof or trunk, where ever you decide to mount your antenna (roof or trunk lid).
I always get asked why I prefer a 1/4 wave spike antenna compared to a gain antenna.
Here you can see that the 1/4 wave antenna has a more consistent higher take-off angle than the gain 5/8 wave antenna.
When we are talking to a repeater that is up on a mountain top 10 or 20 miles away, I want more of my RF signal going up towards the repeater.
I don’t see any difference between the gain antenna and the spike in performance on my vehicles in the past.
Wiring the power lead (the last part)
As with all wiring to a vehicle’s battery system, safety and proper mounting techniques should be followed.
Getting the power lead ( in this case a #8ga wire) is being brought thru the fire wall at a spot that has been my favorite for decades of doing installations.
There normally is a large vehicle wiring bundle that has a rubber boot attached or is a rubber grommet molded to the harness cover that goes from the engine compartment to the interior of the vehicle.
I made a slit with a utility knife about 3/8″ long in the large rubber grommet portion. Below you can see that I had to remove three screws from a pump that was partially covering the location
Then using a 10-12″ long piece of metal rod, I fed the rod thru the firewall while feeling around for an opening behind the firewall allowing me to insert the entire rod, this normally indicates that it will miss equipment under the dash, allowing me to thread the attached wire down to go under the carpet.
Here is where it helps to have someone looking for and listening for the rod as it comes into the interior under the dash as it is being fed from the engine side.
Once the rod appears to be clear of being behind anything under the dash, attaching the power lead should be attached with tape and fed thru.
The next step is to determine how much wire is needed to reach the battery after being mounted with rubber covered metal cable clamps.
Just out of the picture is the high current fuse holder with a 30amp fuse just prior to the battery connection.
Here I notched out a slot for the lead in the plastic protective cover of the positive terminal of the battery (what looks like corrosion is actually a dia-electric grease).
As always make sure you have a good tight clean connection to the battery.
Use the correct size terminal lugs when connecting to the battery.
And the finished installation….
If you decide to do a trunk mount radio installation whether it be a commercial radio or a remoted ICOM or KENWOOD or any other brand, these steps will get you over the hard parts and should you need a question answered, please call me (702-372-9891) and I will attempt to help you, it only takes a few moments to get an answer and get back to what you were doing.
Thank you to Dave W3QQQ for tonight’s audio clip
Good luck & 73
DE WB6AMT Earl
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