GEN 1 Random "Trailer Disconnected" Message when towing a specific trailer

[Dane]

pin 7 is reverse. only used if you have reverse lights

Ok. Helpful. How does the truck use this to detect the trailer connection? Is there a current passed through it? I have a whole other set of questions about if I had reverse lights, but I don't, so I'm not going to worry about that part.

 

[B E N]

You may have a loose terminal in the trailer end connector or a short in one of the wires. A visual check would determine if you have any damaged wires on the trailer. Look for abraded or smashed wiring on the trailer side. Its safe to say its not the truck if it doesn't do it with the other trailer. My guess is you have a damaged wire in the bundle right off the connector and it is opening and closing connections when you bounce down the road.

 

[Dane]

You may have a loose terminal in the trailer end connector or a short in one of the wires. A visual check would determine if you have any damaged wires on the trailer. Look for abraded or smashed wiring on the trailer side. Its safe to say its not the truck if it doesn't do it with the other trailer. My guess is you have a damaged wire in the bundle right off the connector and it is opening and closing connections when you bounce down the road.

I’ll take a good look. But this is a brand new trailer. Doesn’t mean things can’t be an issue, but the wiring is visually pristine.

 

[B E N]

If your handy with a DVOM start running continuity tests and shake the wiring bundle while your checking, it should only take minutes. I would be especially suspect with a brand new trailer. If you had another truck to hook it up to you could double check.

Easy button answer would be take it back to where you bought it and ask them to fix the issue, I would think they would do it free if its new.

 

[Dane]

If your handy with a DVOM start running continuity tests and shake the wiring bundle while your checking, it should only take minutes. I would be especially suspect with a brand new trailer. If you had another truck to hook it up to you could double check.

Easy button answer would be take it back to where you bought it and ask them to fix the issue, I would think they would do it free if its new.

Yeah, I intend to mess with it if it'll dry out a bit and I get a few. It would be handy to know exactly what I'm looking for though - AKA how does the truck actually sense the connection. How many volts, etc - specifics.

As stated, it DOES do this with another truck. My other trailer does NOT do this with my truck (nor the other truck). So it's definitely the trailer. The dealer is willing to fix it - but that's a bit of a pain to arrange (I will if I can't solve it). I was just hoping to eliminate low hanging fruit - which I feel I can do if I can find an explanation of exactly how the truck things the trailer is connected. I just don't know what I'm looking for other than the vague "loose connection", which I haven't found yet.

 

[B E N]

start here!

 

[Dane]

start here!

I'll give that a whirl - but all of the lights/brakes and whatnot work just fine.

So this is saying that there should be power coming FROM the trailer power pin, and you are using the trailer's own battery to test those lights? Seems simple enough, just charged my trailer battery. I expect that will all work just fine though.

 

[Dane]

it senses signal from the 7 pin plug. most likely it will be a wire connection somewhere on the trailer. check the pins to make sure they arent loose

Ok, so this can't be right. I opened up the 7 pin connector for the trailer and it has no wire on 7 (reverse) NOR 4 (Aux 12v).

The plot thickens. Somehow the trailer DOES charge when hooked up to my truck - at least the LED status blinks charging. Now I'm even more lost. There are more electronics at play here than I think I realize. I couldn't find voltage coming off of any other pin from the truck (lights/blnkers, etc all off, so I didn't expect to), but HOW is the trailer charging without #4? How does the truck detect the trailer? I feel like I'm trying to solve an equation without enough data.

Nothing is loose, connections all look fine. Ground seems solid. Also, it did the disconnect thing to me once while I was parked, and not moving in any way, then right back to "Trailer Connected".

 

[Dane]

start here!

Well, everything works fine. Odd part though, I don't have a power pin. It's empty, so I just jumped right from the battery instead. But the trailer itself functions great. Lights, brakes, etc. Nothing looks out of whack. Nothing is even dirty nor rusty. This is a new trailer. I bought it in March or so of this year. It's had a couple small trips and a trip from Denver to Moab so far. I think this is going to have to be a dealer problem, but I'd really like to understand how this works. A buddy's old trailer is exhibiting the same behavior. It'd just be a nice thing to understand how to solve.

 

[Dane]

The plot thickens. I pulled apart my 7 pin connector (Remember, this is a new trailer, never been messed with). I only have five wires. I expected to see six since I have no backup lights. The other wire missing is the 12 volt wire. But here's the weird part. The trailer DOES still charge while hooked up. It has a little indicator light that shows charging. So, tracing some wires it appears that the battery is charging off of the brake circuit. I find this extremely odd - though I suppose it would work, though probably much slower. I'm pretty convinced that the trailer detection runs through the brake circuit as well, so I'm wondering if the shared circuit is somehow causing the truck to think the trailer gets disconnected. Ever seen this five wire setup? It doesn't seem right to me, but this is how the trailer came. There isn't a sixth disconnected wire or anything. There are five wires in the bundle.