Bed lights wired to cargo lights and switch

[fob63]

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What did you do to your Ranger today? | Page 256 | 2019+ Ford Ranger and Raptor Forum (5th Generation) - Ranger5G.com

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[AndyMedic]

What size diode would be needed on the cargo light side to prevent back feed along with the 5-pin relay?

 

[Danager]

No diode required. The relay will disconnect (open) from one side when it connects (closes) the other.

 

[OFC Ranger]

I would also use a relay to provide main power to the lights from the battery and just use the cargo light/switch to trigger the relay, especially being lights in the bed this would avoid shorting out the factory cargo light circuit.

Sound advice. I have learned to relay all things lighting (or aux), no matter how insignificant the power draw may be.

I even have my streamlight base charger and my two Feniex 4200 controllers behind a single relay even though they only draw about a combined total of 3 amps or less.

 

[OFC Ranger]

What size diode would be needed on the cargo light side to prevent back feed along with the 5-pin relay?

You can go on Amazon and buy a 20 or 30 pack of 15 amp one way diodes for less than 10 bucks. I've come to love them. It is how all my lights have two modes (regular and pattern flashing).

 

[micl9]

So I finally got around to ripping out my Aux powered hook up and making the harness for the Battery powered - manual switched OR Cargo light switched hook up.
I have not drilled a single hole in my truck yet, but I may have to get the Crago light trigger wire out of the cab. Tapping in at the rear door threshold right underneath the middle trim piece. White with green tracer wire was right on top!
Here is my plan. Oh and my relay already has a diode built in.

I did it this way so I cant have:

1. With the switch in Cargo light mode the lights will always come ON/OFF with the Cargo lights.
2. With the switch in ON the light s will be ALWAYS ON
3. With the switch in the middle position the lights will be ALWAYS OFF (Stealth mode!).

The big benefit of this arrangement is that you are only relying on battery power, the cargo light is completely isolated.
If you wire as @Bludrok shows you will be adding current draw to the cargo light circuit. While this may be fine as the LEDs don't pull a lot but mine are on a 5Amp fuse which will likely kick a BCM error that the cargo lights are drawing too much current. Is this an issue, maybe not, but better to isolate.

 

[micl9]

Just finished my rewire - should have one this from the start. Sorry did not take pictures
These are the wire lengths I used for my harness and THIS is the toggle I used. I looked for something sexier but no luck, unless you want to drill a bigger hole.

Key thing is DO NOT use the cargo light line as a power source, only as a relay trigger. Regarding the diode - is it required? Maybe not, but better safe than sorry. You are potentially sending a voltage spike back into your BCM. Get a relay with the diode built in.

I am not going to cover everything. You should have some basic knowledge of 12v wiring and relays.

1. Starting at the battery hook up to one of the many studs with a wire with an inline fuse - my lights use 5A. DO NOT run wire without protection, put it in a split loom. I used 1/4 inch. Piggyback on stock harness' and zip tie to them. OP ran the harness in the frame, which I think is fine, but I like to keep things tighter and prevent as much movement as possible, so I zip tied every 6-8 inches.
2. When you get below the rear doors (crew cab) run your signal wire. Remove the threshold trim center piece. This will expose the harness with the cargo line in it. Look for the White with Green trace wire. Tap into this - I ONLY use Posi-taps, never T=Taps! I ran the wire thru the middle mounting point for the trim piece by adding a grommet and removing the mounting clip from the trim piece. On the under side there is a rubber plug, drill a hole in this and run your wire thru it. Add this wire to the split loom containing the 12v wire from the battery and continue to route to the rear of the truck.
3. Once past the rear wheel liner wire things up to the relay and up to the switch location. I used the round hole in the upper rear corner of the bed. I mounted my relay in the exposed area outside the rear taillight cavity with a SS bolt and nut( I have a watertight relay and connector). You could also locate the relay inside the taillight cavity if you don't have a watertight connection.

I am not covering the installation of the bed light - that's up to the type you choose and how you want to install them.
Mine look like THIS. Old 2-way push switch is shown, but that is the same hole I put the toggle in.

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