Tapping Bed 12V for bed lights

[fah3]

I have installed a 12V power supply in my bed and now want to add some LED bed lights. Is it as simple as using a couple of quick connects to tap the positive and negative leads on the wire harness that powers the 12V socket assembly?

Anyone know which wire is the positive? I would assume red is hot and black/white stripe is negative, but would like to know for sure.

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[I_smell_like_diesel]

I simple test light will tell you that pretty quickly. Yes, "usually" Red is B+ and black is ground but you're better off confirming to be safe. Connect the test light to chassis ground and whatever one lights up will be B+ and the other will be ground. Don't use scotch locks or similar quick splices. Sure, they are sleazy easy but they will cause problems down the road with corrosion. I'm a fan of soldering and weatherproof heat shrink or weatherproof crimp connections. Hope that helps....

 

[P. A. Schilke]

I simple test light will tell you that pretty quickly. Yes, "usually" Red is B+ and black is ground but you're better off confirming to be safe. Connect the test light to chassis ground and whatever one lights up will be B+ and the other will be ground. Don't use scotch locks or similar quick splices. Sure, they are sleazy easy but they will cause problems down the road with corrosion. I'm a fan of soldering and weatherproof heat shrink or weatherproof crimp connections. Hope that helps....

Hi SLDiesel

You are spot on. I would recommend looking in splice connectors from Terminal Supply that are used on commercial aircraft for repair. Soldering is not a really good idea as the solder termination of the stranded wire creates a stress consternation that results in wire failure.

Allow me a back story. I managed Ford Trucks Offroad Racing for 25 years. Winning is the only game in this game, and Ford vehicles finishing rate was abysmal, so I did a deep dive and found 75% of the failures were due to electrical issues. I had my offroad team do an inspection of our Ford teams...the results were appalling. So we had ReChem come in with their electric connectors to address the teams... I led the discussion and said that there is no place on an automobile much less a Race Truck for a Scotch Loc. Flip the page a few and I came back from a meeting at Ford Truck to my office when my secretary handed me a phone call note from a 3m engineer. So I called and this guy spewed venom for my statement. I told him that I would not argue with him but would send him a requirements document of what Ford wiring requires and if he could show me the Scotch loc met these requirements then I would rescind my statement to the race teams. My secretary sent him the info and to his credit he called me back to say that it would be impossible for a scotch loc to meet these requirements, to which I reinterated that this is way these things are now welcomed in offroad racing. End result when I retired. Ford's win rate was 75% more than all the other manufacturers combined and this rate continued for the remainder of my career.

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[RangerCat]

For me, the problem with tapping in to the existing power is that it turns off with the ignition. I wanted my bed lights to be available when the truck is turned off. My solution was to run a hot wire back from the battery (with an inline fuse). I was able to run it almost the entire way INSIDE of the frame of the truck. The lights I purchased had an automatic-off feature that will keep them from running the battery down if left on.

 

[Randy2400h]

I spliced into my 12v power port in my bed and then I spliced an optional remote wire into the harness for the tag lights. The lights in the bed come on anytime the lights are on, so obviously anytime it’s running at night, when I remote start the truck, or the truck is unlocked via remote or by touching the inside of door handle. Having the remote wire hooked into the lights is convenient. What IS NOT convenient is how quickly the truck shuts down that 12v circuit for the bed power port after the truck is shutdown. You maybe have 5 minutes before it kills the power. I know that this is a battery saver function to prevent the battery being drawn-down unintentionally, but it means that I can’t plug in my 12v cooler and leave the truck parked on a hot day and expect my cooler to do its job. My truck bed lights have have an 60min auto-off function so having them hooked to continuous power with the remote wire spliced into the vehicle’s lights (which I did) would be the most ideal installation.

 

[RedlandRanger]

I installed a set of LED strip lights and I tapped into the bed power plug. You can see some photos of how I did it here.

I didn't want to cut any wiring and this allowed to to tap it without having to do so, or to use taps. It works really well. For $20, I'm really happy with it.

 

[DBaz]

Hi SLDiesel

You are spot on. I would recommend looking in splice connectors from Terminal Supply that are used on commercial aircraft for repair. Soldering is not a really good idea as the solder termination of the stranded wire creates a stress consternation that results in wire failure...

Agree with you about soldering. I work on wiring harnesses for offroad motorcycles and the gold standard is a good crimp with the correct tool. We use stranded wire for flexibility and durability under vibration...as soon as you solder a stranded wire you create a high risk spot for wire fatigue.

Some think if you crimp and then solder you get the best of both worlds but it doesn't work out that way...you just get more failures. Don't ask me how I know.

Properly crimped connections are also less likely to become corroded due to the gas-tight metal-metal colloidal bond that forms with properly crimped connections. Most solder also has higher resistance than copper.

Probably too much information...comes from wishing someone had told me this stuff years ago.

 

[RedlandRanger]

Agree with you about soldering. I work on wiring harnesses for offroad motorcycles and the gold standard is a good crimp with the correct tool. We use stranded wire for flexibility and durability under vibration...as soon as you solder a stranded wire you create a high risk spot for wire fatigue.

Some think if you crimp and then solder you get the best of both worlds but it doesn't work out that way...you just get more failures. Don't ask me how I know.

Properly crimped connections are also less likely to become corroded due to the gas-tight metal-metal colloidal bond that forms with properly crimped connections. Most solder also has higher resistance than copper.

Probably too much information...comes from wishing someone had told me this stuff years ago.

That is the first time I've heard that crimping is superior to soldering. I've always been told soldering is the best way and crimping is the "cheap" way to do it. I know you can create a good connection with crimping, so maybe it is because it is easy to create a bad crimped connection.

I always hate dealing with electrical stuff and I try and do it right - this is good info for the future.

 

[P. A. Schilke]

That is the first time I've heard that crimping is superior to soldering. I've always been told soldering is the best way and crimping is the "cheap" way to do it. I know you can create a good connection with crimping, so maybe it is because it is easy to create a bad crimped connection.

I always hate dealing with electrical stuff and I try and do it right - this is good info for the future.

Hi Rob,

The terminal supply connectors are crimped, then headed with a match or clicker which causes the shrink wrap to shrink around the wire and while this is happening the glue inside the shirnk wrap heats up so the wire sheath is now glued to the crimp connector making it super strong and waterproof. Really the only way to go on automotive wiring.

here is a pix.... The crimp connectors come in all wire sizes and types, butt splices as shown, terminal rings, spade connectors (male and female) and so forth...

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[fah3]

You guys are all great!! Thanks for the tips and advice.

 

[RedlandRanger]

Thanks for the info Phil. Those are some HEAVY DUTY crimpers! Probably what helps to get you a good connection. I know the heat shrink connectors you are referring to, and yes, when they shrink and the glue sets, it is a REALLY good connection. Heat shrink tubing is not created equal - the stuff from HarborFreight doesn't stick like the better quality stuff does. It just shrinks and that is about it.

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