Wiring work/reverse light

[cmyoung2]

Rewiring a cargo trailer using RV type 7 blade connectors. Plan on using a battery to power interior and exterior work lights when disconnected from the truck , using the always hot lead to charge the battery, I would like to use one of the rear facing exterior work lights as a reverse light (truck connector supports trailer reverse light). How can I wire it so there is no feedback to other lights and nothing fries?

 

[Diamondpilot]

Rewiring a cargo trailer using RV type 7 blade connectors. Plan on using a battery to power interior and exterior work lights when disconnected from the truck , using the always hot lead to charge the battery, I would like to use one of the rear facing exterior work lights as a reverse light (truck connector supports trailer reverse light). How can I wire it so there is no feedback to other lights and nothing fries?

There should be no issues with your plan.

Chris

 

[SSdoxie]

If you plan on using this same light as exterior work light and have more than 1 exterior light, then you would need to run the reverse power to that light with a diode in wire going to the other lights to prevent power feeding to all the exterior lights.
If that light has, could be equipped with a dual element bulb, then run power to second element.

 

[MinnesotaEric]

Rewiring a cargo trailer using RV type 7 blade connectors. Plan on using a battery to power interior and exterior work lights when disconnected from the truck , using the always hot lead to charge the battery, I would like to use one of the rear facing exterior work lights as a reverse light (truck connector supports trailer reverse light). How can I wire it so there is no feedback to other lights and nothing fries?

Make certain your white ground wire is well grounded and properly sized to handle the load from lights and brakes. For example: this improperly grounded ground (the white wire on a standard 7 wire round blade connector) led to blowing out my truck-mounted reverse lights.

As the photos shows, the white wire was not making good contact in the junction box.

My thesis was that when I hit my electric brakes (which draws a lot of power), the four brake solenoids could not find a good enough ground through the white wire and therefore found a path to ground wherever they can--w¡hich in my case was to feedback through the reverse lights circuit and blow everything out. And this on a brand new trailer.

I pulled some slack for the white wire, installed washers above and below the too-big-of-an-eyelet to make a good connection, and tightening the living daylights out of zip-tie so the main trailer wire couldn't pull out of the junction box and put excess pressure on the white ground wire's junction box connection as it had been doing when I found it.

Now the problem is solved. How do I bill the trailer manufacturer for wasting a lot of my time and $120.00 rebuilding my truck's wiring loom?

 

[jaotguy]

a simple 2 way switch ( 3 posts) would work ... power from center of switch goes to the red in the light .... pick one of the switch outer posts and connect to the trailer battery ... connect the last switch post to the vehicle "backup lights" wire ...

when ON with the RV battery , the light draws power from the battery and cannot back feed the vehicle.
when switched to the "off" (other position) , the light only comes on if connected to the vehicle AND the backup lights are ON ...

 

[MinnesotaEric]

I For got to tell you how to do it.

Use the reverse light wire on the trailer on the control side of a relay. In other words, power is supplied to the reverse lights when the truck is in reverse. Back on the trailer, wire a relay in on the reverse light in series (yellow wire, if memory series, but double check that) on the control side and nab 12v power from the 7 pin battery wire (a fat red wire) through the working side of the relay in series out to your work light in series then to ground.

To make the light work when disconnected from the trailer, run two 12v from the trailer's battery (or wherever you tap into unswitched 12V on the trailer) one 12v goes through a switch first, then taps into the yellow wire before or at the relay and shares the yellow wire's ground through the control side of the relay. through the same control side the yellow wire is using on the relay and shares the same ground. The other 12V goes through a 10amp fuse in series, and tabs into the 12v either before or at the working side of the relay.

Confirm good ground from the trailer body to ground on the trailer frame and good ground from trailer battery to the 7 trailer harness white wire, which is ground.

The result: your work light comes on when connected to the tow vehicle in reverse and you can turn the work light on manually with a switch on the trailer.

 

[boggen]

draw yourself up a diagram of all the lights, brakes, switches, etc.... you have on trailer and how they connect. would by my first suggestion. with detail of how the ground wires also connect from each unit.

is there any diodes (think check valve for water, that lets electricity to flow only in one direction)
do you have a fuse box on trailer?
any switches? SPDT (single pull douple throw) or DPDT (douple pull double throw) manual switches you have to flip on/off yourself, relay switches, etc...?

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do you need to upgrade your pulling vehicle electronics / trailer plug to support reverse lighting? or redo any wiring on truck to get reverse to the trailer?

7 pin trailer plug is a big bottle neck...
left turn
right turn
running lights
brakes
charging battery on trailer
stop/brake lights
tail lights
"ground"

in above i just went to 8 wires min on truck/trailer plug. in order to get reverse from pulling vehicle to trailer.

your pulling vehicle trailer plug and electronics need to support reverse going to the trailer. simply tieing into reverse lights on the pulling vehicle can lead to blown fuses on pulling vehicle. to lights that barely light up at all.

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extra stuff....
is your pulling vehicle and trailer already setup to deal with charging battery on trailer? so when vehicle is shut off, you do not drain battery on pulling vehicle? and the charging circuit for battery on trailer setup only to turn on when vehicle is on?

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i just quickly drew up below diagrams, to give an idea how you might draw up some diagrams so you understand what goes were and how..
(paper and color markers work nicely)

COLORS ARE ALL WRONG in below diagrams

.