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Discussion Starter #1
So I just bought some LED's for my trailer since the one of the tail lights failed. I am replacing them all, but all that have arrived are two side marker lights, and my turn/tail oval lights. I tested them today as I had my truck near my trailer and I am only getting one of the side marker lights to work. I have confirmed with a test light, that I am getting turn, and tail light signal to the connector. Then, using a spare battery, I can make all the LED's work on the bench. So, that has me wondering if it's something within the truck itself?? As in, do I need to erase this trailer from the system and then add it back in after all the LED's are installed? Does it have something to do with current draw? I can only assume that is how the truck knows when a light is out. The truck does say the trailer passes the light test.

Open to ideas here! Thanks!
 

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Discussion Starter #2
I had a DOH! move! Made the poor assumption that the color of wires for the new aftermarket light connector would match was was on my trailer. Nope! Had the ground switched with something else. So once I corrected that, the lights work! Did not research if it was my trailer or the aftermarket lights that were wrong, but I am looking forward to longevity of the LED's.

One question still remains. Once I switch all the lights over to LED will the truck still let me know if there is a lighting problem? I did a light test when one of the turn/stop lights was unplugged and the truck said my lights were fine?!?
 

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I had a DOH! move! Made the poor assumption that the color of wires for the new aftermarket light connector would match was was on my trailer. Nope! Had the ground switched with something else. So once I corrected that, the lights work! Did not research if it was my trailer or the aftermarket lights that were wrong, but I am looking forward to longevity of the LED's
One thing people either don't know, or forget about, is that LED's are DIODES and MUST be wired correctly to function. In contrast, you can wire an incandescent bulb with the polarity connected either way.

One question still remains. Once I switch all the lights over to LED will the truck still let me know if there is a lighting problem? I did a light test when one of the turn/stop lights was unplugged and the truck said my lights were fine?!?
Long answer: This depends on the type of lighting circuitry your truck was built with and even then, low amperage loading of the circuit may not even matter. On many 2017 and newer Super Duty trucks, the trailer lighting circuits are still relay isolated and protected with their own fuses and are not monitored by a module. Some of these trucks however are equipped with a trailer tow module which supplies voltage to the trailer stop/turn lamps and these circuits only are likely FET circuits. A Field Effect Transistor (FET) is a type of transistor that the control module software uses to control and monitor current flow on module outputs. The Field Effect Transistor (FET) protection strategy prevents module damage in the event of excessive current flow. In the case of the TRM this strategy appears to be used for lamp out strategy and circuit overload protection. So, by changing your trailer lamps over to all LEDs the only problem you could create is a false lamp out warning on your message center should the module not like the very low current draw of your new lamps.

Short answer: You are good to go.
 

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Discussion Starter #5
Thanks Ford Doc. You have no idea how much you are appreciated around here!

So, before I changed over to LED's I would get a warning if a light was out. So that means I do have the Trailer Tow module correct?

Now, does this system "learn" a trailer's normal current draw and then if that changes, will notify me? What I am hoping to accomplish is to be able to get the truck to once again tell me if a lamp is out on the trailer.
 

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So, before I changed over to LED's I would get a warning if a light was out. So that means I do have the Trailer Tow module correct?
Yes, that is the only way you will be able to get a message center light out warning.

Now, does this system "learn" a trailer's normal current draw and then if that changes, will notify me? What I am hoping to accomplish is to be able to get the truck to once again tell me if a lamp is out on the trailer.
My information does not elaborate on this feature. The module can definitely detect an overloaded or open circuit. It is unlikely that the module is designed to learn or determine the "normal" current draw on each circuit for any trailer. My thinking is that there are set high and low parameters. Either way you will likely get the trailer lamp out warning and a code will be set in the TRM. If I learn more or anything different I'll post it.
 

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Discussion Starter #7
As will I when I pull the trailer again. Thank you!
 
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