Trailer wiring question

[MikeA57]

I've been rewiring my 16' utility trailer and I'm adding an 9 LED light bar on the back of it. It has 3 wires, Red, Black, and White. I know that White goes to ground on the trailer and the instructions state "Attach the Black wire to operate the dimmer illumination of the light.Attach the Red wire to the Stop/Turn circuit to operate the brighter illumination of the light." So I attach the Brown harness wire to the Black LED wire. But the Red wire on the LED bar has me confused. Should I connect both the Green and Yellow harness wires to the Red wire? Or will that mess up the turn signals by doling that? I've attached a drawing showing the proposed wiring as described.

Thanks,

Mike

 

[Smallplot]

Does this light bar have each side flash with turn signals or just get brighter with the brakes? Thinking it should just have a ground and power from your parking lights. If they are designed to come on brighter with the brakes, then you would have to attach the same wire as your brakes (either red or blue). You may have to go back to the axles to get the brake wire as I have seen them switch to the three wire behind the axles to cut costs. If the light bar flashes with your turn signals, then you would have to attach to turn signal wire for each respective side.

Kind of depends on how the light is supposed to function after being hooked up. Need more info!

 

[aczlan]

To use this you will need to connect the green and yellow wires to the red wire with a diode on the yellow and green wires (a diode is like a check valve, it only lets power flow in one direction) OR you will need to tie the red wire into your electric brakes.
If you connect both the green and yellow wired directly to the red wire as shown, you will flash all three lights with either turn signal.

Aaron Z

 

[MikeA57]

Thanks guys, that's exactly what I was thinking. I can route another wire from the brake connection up at the wheel (blue wire) easily. I could wire up the diodes but I'm not sure what size I would need and just running one more wire from the brake will be the easiest route.

The package states that this is a Stop/Tail/Turn light, but with only three connections I don't see how it could be a Turn light. There are a whole bunch of solder joints on the back of the circuit board and if I knew which ones to tap into I could probably convert it to work as a turn signal too, where half of it would flash for one direction and the other half for the other direction. But, I don't need that, I just want it to work.

I probably ought to go ahead and spend some money to have a protective shroud welded over this thing or else it'll probably get broken the first time out!

 

[aczlan]

The package states that this is a Stop/Tail/Turn light, but with only three connections I don't see how it could be a Turn light.

One on each side would make it a turn light just like your existing Stop/Turn/Tail lights.

As for amperage, it should be well under 1 amp, but something like: 6A, 50V Rectifier Diodes (4-Pack) - RadioShack.com should take care of it.

Aaron Z

 

[SPIKER]

As others stated the Stop Tail or Tail Turn combination lights you would need two (2) to include the turn light one for left one for the right.

for marker lights it needs to be set as far out as possible usually within 6" of a side then it can be marker & brake or tail & turn.

Normal wiring attach the "Red" to the brake light so that the BRIGHT LEDs are on with the Brakes. otherwise if used as Tail & Turn then the Red wire would be attached to either the Green or the Yellow depending on if it is on left or right side of the trailer.

BLack wire should be tied to Brown (Tail) light or to "Black" marker/ID lights depending on the trailer color harness you have.

Mark

 

[MikeA57]

for marker lights it needs to be set as far out as possible usually within 6" of a side then it can be marker & brake or tail & turn.

Here's what I picked up:

So it's going dead center on the back of the trailer. Then I've got the 2 normal brake/turn signals on each side of the trailer. I've also got 2 marker lights that I'm considering putting on the sides of the trailer, ahead of the wheels.

I'm using a 7 wire cable with the round connector from the tongue of the trailer to a junction box then I just ran the normal 4 wire trailer cable to the other lights. I also ran a separate 2 conductor cable to the brakes that also ties in to the junction box. This light bar was just an afterthought.

 

[MikeA57]

That's why I got confused; because the packaging said Tail/Stop/Turn and I couldn't see the wires that it had on it with it in the package. Then when I opened it and saw there were only 3 I was like, "What tha...?!?!?"

 

[mjw357]

Should I connect both the Green and Yellow harness wires to the Red wire? Or will that mess up the turn signals by doling that? I've attached a drawing showing the proposed wiring as described.

Thanks,

Mike

If you connect the green and yellow to the red, your turn signals will operate like hazards when you signal left or right. You need to isolate them with diodes as others have mentioned.

The problem with using the blue brake wire is that it is not a full 12v until the brakes are applied firmly, it varies from about 2v to 12v depending on how hard you stop.

 

[mjw357]

That's why I got confused; because the packaging said Tail/Stop/Turn and I couldn't see the wires that it had on it with it in the package. Then when I opened it and saw there were only 3 I was like, "What tha...?!?!?"

OK this is meant to be a left or right S/T/T, not a clearance marker/3rd brake light. You can use it that way I suppose, but again you will have to use the diodes.

 

[aczlan]

If you connect the green and yellow to the red, your turn signals will operate like hazards when you signal left or right. You need to isolate them with diodes as others have mentioned.
The problem with using the blue brake wire is that it is not a full 12v until the brakes are applied firmly, it varies from about 2v to 12v depending on how hard you stop.

Good point. Diodes on the green/yellow wires are your best bet if you want to use this in the center.

Aaron Z

 

[Smallplot]

Here is a thought. Before attaching the light hook up some wires and check out what they do. Just cut a couple jumper wires and pull directly from your trucks plug. Pay special attention to how it does with right and left turn signal. The outside two lights my flash giving an auxiliary turn signal. In that case you would have to attach the coordinating turn up to the appropriate wire and parking light wire up to the third wire.

There should also be a wiring diagram on or in the package. It may be able to act in several modes depending on how you want it to operate.

 

[MikeA57]

Yeah, I was just going to use it as a rear tail and brake light. It was cheap enough and I knew that 3 quick holes drilled and a simple hookup, I'd have it installed. Then this...

That's a good point about the wire from the brake. I knew that but didn't think about it. Maybe I will just use the diodes. I've got some lying around.

 

[MikeA57]

There is no diagram on the packaging or website. The instructions are printed on the back of the cardboard sleeve. I thought this was supposed to go in the center of a boat trailer and work the way I wanted it to. Just another example of me wanting the world and everything in it to acclimate to my will and not the other way around...

 

[Iplayfarmer]

Even if you hook the center light up with diodes, it's still going to flash when you use either turn signal. The only time it won't is when you brake while you're applying the turn signal.

My suggestion... Connect the black wire to your marker circuit and forget about the red wire. Problem solved. You have a clearance marker light on the back and you don't have to worry about isolating the turn signals from each other.

 

[simoutdoors]

You guys are over thinking this. The ground/neutral is likely provided by the mounting bolts, which is typical in trailer wiring. Now you have one wire for running light and one to connect to each brake light/turn signal.

 

[Iplayfarmer]

You guys are over thinking this. The ground/neutral is likely provided by the mounting bolts, which is typical in trailer wiring. Now you have one wire for running light and one to connect to each brake light/turn signal.

I guess the easy way is to hook up a battery charger and test it. I'd bet that the white is ground, though.

 

[boggen]

someone else said. grab the light, and just hook it up directly to the wiring harness at rear of truck. with some jumper cables or like. and see what happens.

jumper cables being. a couple pieces of wires. ran from wiring harness to cables on light. and piece of tape around each connection.

if need be have a second person help you. as in, applying brakes, left and right turn singles, flashers on/off. turning on / off tail lights.

just a side note, i assume you have ample power for additional lights. but you might have a cheap extra flasher unit. for tail lights. that may not have enough umph to run all the extra lights.

the idea of running lights off the wire to the trailer brakes. has me on edge. just does not sound right. i mean technically it could work. but doing so could cause the brakes not to work correctly on the trailer. or rather make that, the brakes would not apply themselves as good as they did before if you ran light off of the brake wire.

================
on another note:

if you are placing this dead center, i would just use it as a marker tail / brake light. and forget idea of turn singles in it. if you had 2 of them and placed each one on left and right side, OK. but dead center. I don't know about the idea of using it as turn singles.

 

[Iplayfarmer]

...if you are placing this dead center, i would just use it as a marker tail / brake light. and forget idea of turn singles in it. if you had 2 of them and placed each one on left and right side, OK. but dead center. I don't know about the idea of using it as turn singles.

The problem here is that trailer wiring doesn't usually have a brake light option. There are marker lights and there are "signal" lights. The same wire runs the turn signal and the brakes. If you apply the brakes, both lights come on. If you apply a turn signal, only that one side comes on (and blinks). The challenge is how to illuminate this center light when the brakes come on, but not blink when a turn signal comes on.

I don't see a good way of doing it. Even a 7-way trailer plug doesn't have a dedicated brake circuit other than the electric brakes. I agree with others that tying into the e-brakes is a bad idea. You could run an extra wire, but I couldn't even tell you where on the truck to pull the power from. Your signal lights on the rear of the truck are likely wired the same as your trialer (i.e. no separate brake circuit)

 

[Iplayfarmer]

New idea...

Is there a way to wire this center light so that it only illumintates when BOTH signal lights are on? This way when both signal lights come on (i.e. when braking) this center light would come on. When only one is on (i.e. when applying the turn signal) the light would not come on. I'm sure there's some kind of relay or something that would require two inputs in order to energize the output.

Oh, Dang! That still gives you a blinking light when you apply the brake while you're turning.

Nevermind. I'm back to just wiring this center light as a marker light and leaving well enough alone.