Can anybody confirm the function of this trailer-lights box?

Gypsy62 · **Posted:** Wed Oct 23, 2019 2:13 pm

Link to pic:
https://www.dropbox.com/s/bllqylxbv6e8u ... 1.jpg?dl=0

I suspect that it is an OEM component included with the Liberty's 'Towing Option'. I removed it to install an RV toad setup on a previous '05 gasser's tail lights. My probably-wrong best guess is that it converts the Jeep's independent blinker & brake circuits into a ganged-yet-separate circuit that will work with a flat-four trailer-plug setup(?).

Presumably, universal-assignments apply: Green/Right, Yellow/Left [mnemonic device = "R"'s and "L"'s], Brown/Tail, White/Ground, Red/12vdc.
Okay, but what does the box do???

Related, I'm going to wire a 'Round 7' trailer-plug to my CRD for local 'tractor duty'; any advice appreciated.
To handle heavy tongue loads I've already installed Airlift Airbags inside my new OME rear-gear. For its air supply I T'd into the ARB compressor for the F/R lockers.
Installing a Tekonsha P3 trailer-brake controller this week.
The round-7 plug is the last hurdle.

That is, except for the slight problem of getting the jeep running again after 7-months of turbo-replacement hassles :ROTFL:

[Another post]

Keys: t-shooting trouble-shooting trailers Jeep CRD trailer-brake brakes wiring wire wires, jeep diesel liberty trailer plug problem

TKB4 · **Posted:** Thu Oct 24, 2019 11:06 am

That appears to be a converter similar to this:
https://www.amazon.com/gp/product/B005S ... UTF8&psc=1

that converts a vehicle that uses a separate wire for the turn signals and the brake lights. It converts that type system called a three wire system to the standard system for trailers know as a two wire systems. Some of these converters on certain vehicles also require addition of resistors to work normally with LED bulbs.

I don't believe there is any box like that from the factory. Most likely if you bought it used it was added by a previous owner . There are also ones that just plug into the connection to tail lights then original tail light connector plugs into it so no soldering or butt connections etc except maybe attaching a ground wire.

If your CRD came from the factory with a towing package from the factory it should already have a 7 way connector but the connector won't operate brakes without purchasing a brake controller and modifying /connecting a wire from under from driver side console to the 7 way plug.
If you read on the link picture I think that one uses the red for the brake lights. There also may likely be different color on input than output side of these type connectors at least for one wire.

I got the plug in type from trailer for one CRD it is very easy. You can then get a 4 way to 7 plug adapter for vehicle side of 7 way or you can probably get the 7 way plug without separate 4 way conversion but it still only does the 4 way functions or at least not the brake controlling.

I got my kit from e trailer and it worked well to 4 way flat. I have also added brake controller to a factory 7 way plug. I would check one trailer etc for a direct plug in unit its very quick and easy then just need to hook up brake controller with the blue wire under driver foot area . If you want the 12 volt wire to charge trailer battery etc you may have to run separate dedicated wire for that not sure I didn't need the 12 volt prong so didn't hook it up but it could have been connected from factory I don't know.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

TKB4 wrote:

I don't believe there is any box like that from the factory. Most likely if you bought it used it was added by a previous owner . There are also ones that just plug into the connection to tail lights then original tail light connector plugs into it so no soldering or butt connections etc except maybe attaching a ground wire.

If your CRD came from the factory with a towing package from the factory it should already have a 7 way connector but the connector won't operate brakes without purchasing a brake controller and modifying /connecting a wire from under from driver side console to the 7 way plug.

I'll confirm the above. Our KJ has the factory tow package, and only has a 7-pin connector at the hitch. The 7-pin connector is a Chrysler part per the logos and part numbers moulded into it, and the towbar (IIRC) has the factory stickers on it describing how it's intended to be used. It also appears on the build sheet, so is almost certainly not aftermarket.

WWDiesel · **Posted:** Thu Oct 24, 2019 2:58 pm

I will also confirm it looks like a converter box.
I have installed many of them on vehicles that have separate turn signal light circuit from the brake light circuit on the rear of the vehicles. Toyota's, Nissan's, etc...

The converter box takes the two distinct and separate input circuits (signals) and converts them into one circuit for trailers that only have a single dual filament bulb like a 1157 on the rear. One filament is for running or tail lights and the other filament is for the brake/turn signal light combo.
This allows the brake and turn signal circuit to be converted into a single circuit going to the trailer light. The converter box can be used on a multitude of trailer connectors like the 4-wire flat and the 7 pin round.
If the Jeep, or most any vehicle for that matter, came from the factory with a trailer towing package and has a trailer wiring connector, it normally will already be wired and provisioned with the correct two into one circuits for a trailer. But if you have a vehicle which did not come with factory installed trailer wiring, and it has separate turn signal lights and separate brake lights, a converter box will have to be installed for proper trailer light signal operation....

Sometimes a picture makes things easier to understand.

Gypsy62 · **Posted:** Thu Oct 24, 2019 8:31 pm

Thanks for the diagram! That should greatly assist in identifying the coverter boxes wire assignments. It should still be useful; maybe I'll sidecar a flat-four near the Round-7.

At least I was half-right (shocking). Not OEM, but it does convert the independent blinker & brake inputs to a ganged circuit output for a flat-four setup. Cool.

Thanks for the insights on the Round-7 trailer plug & brake-controller setup.
I'm going to endeavor to make the Round-7 connector fully-functional, including reverse & 12v supply (w/relays).

All suggestions appreciated.

Can anybody confirm the function of this trailer-lights box?

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