Splicing into 12V dc Circuit

[slow]

I am looking for thoughts on the most appropriate way to splice into a 12V dc circuit.

The project I am undertaking is wiring in a rear observation camera using a relay, the driving lights to switch it on, and the power source from my converter's distribution panel. Unfortunately all eleven 12V fuses are in use.

Mapping out the unlabeled fuses, I found a couple that only supporting one or two lights in a couple of areas. Those lights have LED bulbs. My thought is to splice together the two circuits (within the converter?) supporting the three LED light loads to free up a 12V fuse for use for the camera's power.

The options that come to mind are:
* use a fuss tap for the extra circuit - but prefer not to have more weight hanging off the circuit board
* connect the two existing circuits at the bus bar under one screw - I suspect this is not acceptable practice although the ground bus bar is wired this way
* use a terminal block to splice the two existing circuits and tie it into one fuse
* use a splice connector to splice the two existing circuits and tie it into one fuse
* use a twist on Marr connector to splice the two existing circuits and tie it into one fuse
* solder to splice the two existing circuits and tie it into one fuse

Any other options or preferred method for long term durability/safety?

[bsmith0404]

Not sure about your intended use, but if it were me I'd just tap into the back up light wire. Your 7 pin connector has a wire for backup lights, some RVs may cut the wire off at the junction box, others may have the wire run to the taillights with the other taillight wiring. The backup camera doesn't use much power so your current truck fuse should be fine. With that setup, the backup camera will activate anytime you put the truck in reverse.

If you don't want to go that route, I personally like to use an add a fuse adapter.

[slow]

Not sure about your intended use, but if it were me I'd just tap into the back up light wire. Your 7 pin connector has a wire for backup lights, some RVs may cut the wire off at the junction box, others may have the wire run to the taillights with the other taillight wiring. The backup camera doesn't use much power so your current truck fuse should be fine. With that setup, the backup camera will activate anytime you put the truck in reverse.

If you don't want to go that route, I personally like to use an add a fuse adapter.

Thanks for the insights Brent.

To add some more info for why I am doing this project: I am currently tapped into the running lights because my camera is for observation while travelling forward (simulating a rear view mirror), not backing up. The voltage is just under 12V after the long cable run and is not clean (makes the image fuzzy when braking or the turn signal is on). That is why I will use a relay triggered by the running lights to get a "clean" 12V power source.

[bsmith0404]

In that case, why not just run a dedicated wire directly from the battery? All you would need to do is put a quick disconnect like a bullet connector in the line so you can easily turn the camera off when uou stop. If you want to protect it with a fuse, just wire a link into it. I always look for simple solutions with limited probability of failure.

[slow]

That is possible. Easier to switch camera with running light switch in TV and converter is at center rear of TT. Therefore was thinking I could avoid running 25+ feet of wire.


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[slow]

I ended up going the solder route and am happy with the result.

Here are a few pictures of the steps I took based on searching the internet for automotive wiring splicing:

https://uploads.tapatalk-cdn.com/20170717/d39076ae2ec2576dfb67e82e68c05a79.jpg

https://uploads.tapatalk-cdn.com/20170717/65620f794f3a92c599f70c4531069072.jpg

https://uploads.tapatalk-cdn.com/20170717/bbe2d50ad45a81ca154fd61a67bc803c.jpg

https://uploads.tapatalk-cdn.com/20170717/bbe41064577aaa207acf6839e3c7d87a.jpg

https://uploads.tapatalk-cdn.com/20170717/e281d46eac24169fed59cf65f9994c99.jpg

https://uploads.tapatalk-cdn.com/20170717/4c677b69df9bc65b8162f7abce2c55c0.jpg

https://uploads.tapatalk-cdn.com/20170717/0d410a5bf2b83fa31aebd5018c12805d.jpg

https://uploads.tapatalk-cdn.com/20170717/1d43712a18bcd6ff0c344d0f45d37fe9.jpg

The 8th fuse slot was made available and is now used for the power (solid red colour wire fourth from the bottom) via a relay for the rear observation camera. I turn the camera on by turning on my driving lights.

[MattHelm21]

So, in the same vein, I have a factory camera system with a dedicated power switch and a rocker on/off switch. This switch actually controls power to two cameras, one in the garage and one above the ramp door which I use as a didicated rear view while traveling. I have a checklist item to make sure to turn this switch on before traveling and usually remember but frequently forget to turn it off after unhitching. Utilizing a relay to control this circuit from the running lights instead of or in addition to the rocker switch would make life a lot easier. Any idea what type of relay might do the trick for this? I'd also have to find a place to tap in to the running light from inside the garage if possible since the dedicated wiring and rocker switch are located there.

[chuckster57]

Very clean! Wish we were given enough time to do that good of work.

[slow]

........... Utilizing a relay to control this circuit from the running lights instead of or in addition to the rocker switch would make life a lot easier. Any idea what type of relay might do the trick for this? I'd also have to find a place to tap in to the running light from inside the garage if possible since the dedicated wiring and rocker switch are located there.

Using the running lights to power the camera really makes it convenient for me. I use our Garmin 760 GPS for the display, and when I turn on the running lights, the GPS display changes to the camera.

This is the four pole relay I used, should be able to find the equivalent on Amazon or local auto parts store:http://www.canadiantire.ca/en/pdp/pilot-automotive-40-amp-relay-0203760p.html

Here is my chicken scratch sketch for the wiring:
https://uploads.tapatalk-cdn.com/20170717/f20f6206c11374c79dc32d862603cbff.jpg

My running light wires were run under the TT and were easy to access by dropping the comoplast at the rear of the TT.

One thing that initially threw me off was that the TT's running lights were powered with the green not the brown wire. It may be unique to my trailer, but worth noting and checking before cutting wires.

[MattHelm21]

This is my next downtime project. I did my own camera install on my last fifth wheel without a relay but powered from the running lights and ran into the exact problem you described. Thank you for the diagram, part number, and blazing the trail. :)

[slow]

Very clean! Wish we were given enough time to do that good of work.

Yes it does take longer than crimp connectors!

I only needed one multi-wire connector, but I could only find packages of 12 for $34 locally. So it was worth taking the extra time to solder.

[slow]

This is my next downtime project. I did my own camera install on my last fifth wheel without a relay but powered from the running lights and ran into the exact problem you described. Thank you for the diagram, part number, and blazing the trail. :)

Please make sure to post how you did the project when complete.