Running lights always on

[Munchie]

Not sure where I should start to solve my problem. I have a 2021 Chevy 2500 diesel and 2021 globetrotter FB 25. My problem is that when I’m towing and stop for any reason and turn off my engine my marker lights stay on. When I unplug the 7 way from the vehicle they go off. I’m also noticing that my vehicle doesn’t seem to charge my batteries when driving. Any ideas where I should start?

[John Ware]

Sounds like the 12v feed and the marker light wires have been swapped either in the female end on the truck or in the male end on the trailer.

[InvertdEagle]

Get something like a CURT 7-Pin RV trailer wire vehicle socket tester like this one:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

They're cheap, and tell you exactly what pins on your truck are "hot" and have voltage. Helps when diagnosing all sorts of lights & electric brake issues. Best $11 you'll ever spend. Lots of different ones on the market that do the same thing...there's no difference in function.

[TitusNW]

I agree with JEWare, probably swapped wires and my first guess it's on the trailer end. Testers are great and I'll admit I've gone a bit overboard with my tester but trailer wiring drives me nuts when it doesn't work as expected.


I'd try to put 12v on the trailer connector terminals between the "standard" ground and marker terminals to check the trailer first. The newer trucks are a crap shoot of what's powered or not depending whether a trailer is connected or not (hence my test rig!)


Steve

[Munchie]

Thanks everyone. Good info to start the diagnostics.

[uncle_bob]

Hi

Keep in mind that even *with* things hooked up properly, charging batteries as you roll down the road is problematic. There is a lot of voltage drop (relative to a battery charge voltage) in the wires that get back to the trailer.

Do any of your truck lights stay on after you get out of the truck? On mine they do for a while. While they are on, the marker lights on the trailer are also on. Once the truck decides to actually turn everything off, the marker lights go out.

No, I'm not betting against the crossed wires, only trying to fill in the list if it turns out to not be the case.

Bob

[Escape_Plan]

Similar issue with my Ram diesel, bought a 7-pin pigtail to go between the trailer and the truck since the standard trailer 7-pin cable on the Airstream wasn't long enough with my ProPride hitch installed. Well, it was long enough, but would really stress the cable on left hand turns. Anyway, I bought the parts and was going to build the pigtail, but the guy at the store (horse and farm supply) said he'd do it. Well, he wired to pins wrong. Lights were always on as soon as I plugged into the truck whether the truck was running or not. Once I sorted that out, the position lights on the trailer still remained on when plugged into the truck. Long story longer, as it turns out when I connected the mis-wired pigtail, it blew a fuse on the truck.

Moral of the story: once you get the 7-pin sorted, you might want to take a look at your fuse panel on your truck.