Switch wiring question

I probably already know the answer but would very much appreciate confirmation. Searched but came up lacking, sorry if this is a dumb question.

Have bed light strips installed currently with a manual switch under the bed rail. Powered up with +&- tapped into the trailer plug. Am wanting to install a master lighted switch in series mounted in the dash and powered full time independently of running lights.

Is my wiring diagram correct below?
Is there another full time tap point under the dash?


I understand I can probably pick up a ground somewhere in the bed area but am using 2 conductor wire so figured to just run it back to the dash or battery negative if needed.

Any help with advice is appreciated.

 

That should work .

Why keep the second switch ?

Unless you need the option to control the lights outside the truck after switching the cab switch on.

 

Two separate sources powering the same load typically requires a diode installed to keep one source from back feeding the other. The diode basically is a one way valve. Not 100% sure it's needed from the info you gave but the diode is very typical for on load that can be turned on from two sources.

 

I might need additional clarification before making any precise recommendations; however, the above comment concerning diodes gives me a sense of what might be going on.

Indeed, if you are feeding power (signal) from two different sources then diodes will be necessary. Google "Schottky Diode". Specifically, that is the sort of diode you need. Use a voltage meter to determine what size Schottky diode you need. More, educate yourself on the difference between cathodes and anodes; direction matters with diodes. In other words, it matters which direction the cathode and anode points towards.

Second, you did not share any information concerning amperage draw. However, given your use-case, it seems to me that a relay makes sense here nevertheless.

The first problem you need to solve is how to join the signals into a single signal. The following outlines a method which I like. Find a mini power terminal on Amazon. Feed your bed light and switch signal into that power terminal. As previously mentioned, solder some diodes on each line feeding into that power terminal to protect your upstream device / switch. Using spade terminals, you can join these separate signals without soldering. In other words, run a small wire from one terminal to another. The spade terminals will touch, resulting in signal from either switched or bed light source. From there, feed that signal into a relay. From there, add wires for the ground, battery power, and bed light output.

These configurations can get ugly and unmanageable, even dangerous. Put some thought into managing your electronics with a fuse and relay box, such as the Eaton Bussmann or a small piece of aluminum sheet metal with drilled eyelets for attaching relays, fuse boxes, etc.

Lastly, if you need to tap into any factory wires - use open barrel crimps with heat shrink, soldered connections with heat shrink, or solder seal wire connectors which serve both as heat shrink and solder in one.

Use high quality materials. Do not skimp on heat shrink. Avoid braided sleeving if possible, assuming your wires will be exposed to the elements.

 

Sorry fellas. Let me clarify. Bed lights were wired with +&- tied to trailer light plug. Meant I could only use bed lights if keys were in ignition and switched on or to accessories and running lights turned on. I am rewiring so it's powered off the battery, only one source, with a master switch on the dash and another in series at the bed under the rail near the tail gate. Only one source and from battery, have cut loose trailer light plug feed. So final wiring should look like diagram shared in first post. I don't think that needs a relay since it's one circuit with two in series switches. Very small amp draw, think the fuse that came with lights is a couple amps, will double check but am sure it's fine.

 

Assuming it's currently grounded, there would be no need to change that part at all. Just add in the new power lead from the battery as shown in your drawing. 2 inline switches will not affect each other, other than they would both have to be "on" for the light on come on.

 

Thanks, that's what I am thinking. Agree on the ground at the plug but since I was using 2 conductor wire I am just running back to the battery with the ground. Also cleaning up some previous wiring for back up camera while I am under there. Thanks for all the advice.

 

If the amerage draw is low and your bed light signal is fed by a single source then I concur - forget the relay and diode(s). Use, like you said, simple fuses. It might nevertheless be worth running an auxiliary fuse box but it sounds like you can manage just fine.

As a final clarifying point, make sure you go one gauge larger wire than you think that you need. For instance, if you imagined using 20 gauge - use 18 gauge instead. Personally, I use 16 gauge SLX wire for these sorts of things just to be safe. You are, after all, running wires along the length of the truck it sounds like - so be prudent.

Hit me up if you want recommendations for wire, heat shrink, dual-wall heat shrink, etc. I have experimented with many different materials.

Good luck.

 

Switch came in today and is in and working as planned. Direct fit in blank between dimmer knob and steering column. Only revision is a ground for the lighted switch, diagram in op is missing that.

$18 00550-35976

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