Mystery box in trailer connector wiring

[Lindenberg]

The left blinker quit working on my tow car so I began the process of tracking down the problem. Yes, the bulb is good. The trailer plug (left blinker connector only) on the back of my Alpine was dead so I went further upstream and discovered a mystery box. It is wired into the wire harness that runs between the trailer connector plug and the main wire harness that runs to the dash connector. This box is about the size of a deck of cards and has four wires going in one side and out the other side. The box is sealed, can't be opened and doesn't have any markings on it.

Any ideas?

[Lindenberg]

The left blinker quit working on my tow car so I began the process of tracking down the problem. Yes, the bulb is good. The trailer plug (left blinker connector only) on the back of my Alpine was dead so I went further upstream and discovered a mystery box. It is wired into the wire harness that runs between the trailer connector plug and the main wire harness that runs to the dash connector. This box is about the size of a deck of cards and has four wires going in one side and out the other side. The box is sealed, can't be opened and doesn't have any markings on it.

Any ideas?

[Tom in Salem, MA]

Sounds like an "active taillight converter".
Check out this link, does it look like this?
Good Luck!
Tail Light Converter
edited to correct link

[Old Scout]

"Not exactly"--I dont know the specifics but some brands of car/truck, foreign/domestic use a different wiring config for the brake and turn lights. For example, our 2003 Alpine required a "converter box" to be compatible with our Chev Pick-up. I'd make sure all the spices up/down stream are good before replacing the box....

[Tom in Salem, MA]

I never suggesteded that he replace it, just trying to help him figure out what it may be from 3000 miles away.
Now we have two ideas that he can look into....."exactly".
You Wrote
"I'd make sure all the spices up/down stream are good before replacing the box...."
It's usually the corriander that's the culprit

[dgerstel]

Tom,

Our 2002 had a "converter" in the trailer light wiring, which caused problems and had to be replaced. These usually have three wires in, left and right turn signals and brakes. And two out, left and right, turn signal and brakes combined. This is accomplished with internal diodes. These diodes will fail in time and the unit will need replacing. You can test the wires going into the unit from the main wiring harness. If the power is OK there and not on the output then you know the converter is bad. These converters can be gotten at most any auto parts store.

[midflalpinetec]

It's a 3 to 2 converter box aftermarket installed for your tow viechle

[rmmpe]

Note: if the towing vehicle has seperate signal lights (like my Alpine), a converter is only required if the TOAD's tail/brake/signal lights are dual filament bulbs. If the TOAD has a bulb for the tail/stop lights and a seperate bulb for the turn signals, a converter is not required. Wire those directly through the plug.

I've had both and have never had good luck with a converter, which is why I made and installed a seperate/removable lighting system for our Edge TOAD.

Electrical systems can be somewhat problematical by nature. And, as everybody knows, it's not nice to fool with Mother Nature.

[diceman1530]

if you look at the wiring converter they are only made to handle a very small load.on my coach after i installed a new converter box i hooked the box up to relays to carry the load.the converter now only turns on and off a 1/4 amp relay.it hasnt bin a year yet but no failure of the box.

[Dave & Colleen]

Diceman 1530 & RMMPE
That relay makes more sense to drop the amps. That's one issue, I haven't looked at as I had a shop install the electrical for our Toad. Works fine, but just haven't even researched how they did it. Could you post the relays used and the diodes used or send the numbers to me.
Thanks
Dave

[dgerstel]

While I have been known to "over solve" a problem, I wouldn't go to the trouble to add relays to these circuits, unless you are pulling a trailer with many brake/turn lights. The one I had to replace was about 5 years old. We are only talking about powering one brake/turn light per circuit on your average tow car. Now a trailer with many marker lights could use a relay for that circuit, especially on the coaches with the Vansco system.

[rmmpe]

Also, if your TOAD has LED lights, the load is insignificant. Besides, the converter is made to handle the added load of the TOAD lights. But, I still don't like them and would go another way.

Although I don't see reference to it, I assume your MH has separate run/stop and signal lights and the TOAD has combined run/stop and signal lights (or vice-versa). If the MH and TOAD do not have different light arrangements, a converter is not required and only gets in the way.

I'd concern my self with fixing the current issue before I considered relays.

Dale,
I, too, have been known to "over-solve" problems. I have relays all over the place. But none in the regular lighting system(s).

[diceman1530]

i have bin on the side of the road with my friends prevost too many times, thats why i went to the relays,we pull pretty large trailers that have a fair amount of lights with our coachs.its always raining or cold when the lights stop working.i had replaced two converters before i went to the relays.
used standerd bosch fog lamp relay 30 amp

[dgerstel]

Diceman,

You got that right!!