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Dash Cam Wire Splicing Guide

How to splice wires together for your dash cam

How Wire Splicing Works

Wire splicing and soldering is a core concept that electricians and technicians will be plenty familiar with; describing the core concept of fusing and connecting 2 different cables together.

As experts in the dash cam field, we at BlackboxMyCar recognize that sometimes, setups aren’t always a perfect fit for certain vehicle models, and that certain pieces of equipment will need to be altered to work properly together. This is why we splice our own cables in-house, mainly focusing on extending hardwire kits, and splicing battery output cables.

The advice here will be generalized and somewhat applicable outside of the dash-cam field, but will primarily be focused on dash cam wiring, which is our niche of expertise. For splicing advice in other fields, consulting a local electrician is advised.

Not looking to go through the hassle of splicing? We sell pre-spliced cables here, and extended cables here.

Tools you’ll need:

Basic Soldering Iron

Wire Strippers/

Tin-lead 60-40 Solder
(Rosin core 0.6mm used)

Properly Size Heat-Shrink Tubing

Heat Gun/
Soldering Gun

For wire extensions:
2 variants of the same cable to be extended

For battery splicing:
an unspliced output cable + a dash cam 3-wire hardwiring kit

A suitable environment to splice, such as a workbench (Away from flammables, with a suitable place for soldering to drip)

Tools to grip and hold firm the wires in an elevated position

Why is splicing needed?

So, for this example, we are connecting and soldering an unspliced output cable for one of our battery packs, the PowerCell 8 to a standard 3-wire hardwire kit for one of our Thinkware Dash Cams.

The reason this is needed is that many dash cams on the market rely on a 3-wire connection to go in and out of parking mode, as the ACC (Ignition-based) line of the hardwire kit sends the camera in and out of parking mode, conveying with the vehicle turns on and off. This is straightforward enough when wired directly to the car battery. However with a battery pack, the camera stays permanently connected to the battery pack instead of the vehicle, and if a constant 2-wire connection is wired to the battery from the camera, that information on the vehicle’s status is lost.

Wiring a 3-wire connection between the battery pack and camera allows the camera to go in and out of parking mode for many camera models. This splicing is required for these two to be properly compatible, and when a battery and dash cam are purchased together from our website, we splice a cable together for this purpose, allowing it to be a simple connection for you when you receive them.

Splicing is not required for all camera brands, as BlackVue cameras for example, can go in and out of parking mode based on detecting if the vehicle is moving. It will go into parking mode once the vehicle has been left idle for 5 minutes.

Step 1: Stripping the wires

Let’s get into it! Grab both your unspliced output cable for the battery and hardwire kit for your dash cam. Here, you’ll note 3 wires that should have tags/labels respectively. For this example they are tagged: Yellow(ACC), Red(Constant/Bat+), Black(GND)

Both cables should have tags labeled as so, and for this example, the colours are matching, so Yellow to Yellow, Red to Red, Black to Black all makes this very simple. However, the coloration of the cable does not indicate the connection type inherently, and the tags on the cables should always be consulted before wiring; it’s fully possible you’ll need to wire red to yellow and vice versa, depending on your equipment.

Now, let’s get these wires stripped, and prepped for a connection. For this, a dedicated wire stripper is easiest, and inserting the wire’s connection tips into the machine, and pulling the trigger will result in what we want, exposing the bare cable inside. We are looking to remove the coloured insulation of the cable, so that the bare wires underneath are showing, to connect to the other cable, approximately 1 inch of the bare wire should show.

A dedicated wire stripper is not required, and this can reasonably be done with a wire cutter, typical knife, or even by pulling hard enough with pliers. If the bare wiring becomes frayed, or strands are broken during this process or any further step, feel free to cut off that segment of the cable, and expose more bare wire to use instead.

Step 2: Connecting the Wires

Now that all our wires are properly prepped, we can get them in position to be connected. Here at our splicing station, we have two alligator clips to hold the wires, so we’ll put one in each. Take your heat shrink tubing, and slide that onto the side of one of the cables. This will make sliding it overtop the splice easier later. The heat shrink tube should be fitted properly according to the wire, the tubing should be relatively snug on the cable, and not too loose.

With the bare wire of both cables exposed, grab both and twist them around each other until they hold relatively firm, and the wire ends are not poking out.

Step 3: Coating the wires

Now that the wires are properly connected, we can focus on making sure they stay that way, by coating them in the Tin-Lead Solder. To do so, grab the Tin-Lead cable and your soldering iron. Above our conjoined cable, melt the solder to coat the wires. You want the outline of the wires to be visible, but no bare wire showing, and no globs of solder on the cable. In the words of our splicing expert: Don't be stingy with the solder! Coat it on there.

Adding extra heat to the bottom of the cable is advised with a heat gun, which will help the solder melt into the wire itself, instead of resting on top of the cable, which we do not want.

3M Silicone paste, or Soldering Flux can be applied to the connection before soldering to help in the coating process. This should be coated in the cables before coating.

Step 4: Sealing the cable

With the solder done properly, and the wires coated, let’s get our fine work sealed so it can’t be bothered later. Here, the heat shrink tubing put on one of the cables earlier will help us. We can shimmy that overtop of the soldering.

Once covered, we can use our heat gun to shrink the heat shrink, and seal the section of the cable. Start using the heat gun on the center of the cable. Ideally, a properly sized heat shrink tubing will be flush with the rest of the cable.

Don’t heat the rest of the cable too much, or it runs the risk of shrinking as well.

All steps must be repeated for each connection to splice properly.

We Sell Pre-Spliced Cables

Sometimes a cable isn’t quite long enough to reach where it needs to, for example hardwiring to the rear fusebox of a BMW with your Dash Cam sitting up front. For this, you are able to manually extend the hardwire kit, following a very similar process.

While the procedure is basically the same, the equipment will differ. You’ll need to cut a section of the existing wiring, and solder on a comparable cable, or even another of the same cable. For extending hardwiring cables, we use a 24AWG 3-core set-up generalized cable, instead of wasting 2 cables.

For cable extension, the spicing must be done in 2 different locations of course, as opposed to the single connection of the hardwire kit.

While splicing is possible on additional cable types such as Coaxial front/rear cables, or USB cables, this advice may not prove applicable, as we mainly focus on extending dash cam hardwiring kits.