Check Trailer Connection

[Doug Hawkins]

Just hauled a trailer for the first time with my new 2026 2500. Every time I started out from a stop, I got a "check trailer connection" alert along with the chime. I've hauled this trailer with my last truck, no issue. Things seem to be working OK, so that alert is gonna drive me nuts. I stopped on the side of the road, unplugged and re-plugged the trailer connector several times, making sure the connector was seated as far as I could push, thinking maybe I might have some corrosion preventing one of the contacts from electrically connecting and hoping to wear it off a bit. Didn't help. The truck clearly knows a trailer IS connected, so I'm not sure what the issue may be. Anyone know WHICH of the pins the module might be "testing" and causing this error before I take it to a dealership?

EDIT to add that recall 03D has been done according to the RAM App.

 

[Rlaf75]

Are you using a 4 pin or a 7 pin connector? Make sure the trailer harness fits snug and is not wiggling. A loose connection could cause a contact failure possibly triggering the warning

 

[Fake-Account27]

Have you pulled the breakaway on the trailer by accident? I would also buy a 7 pin tester so you can check if its your truck or your trailer that is having issues.

 

[Doug Hawkins]

1) As the vehicle is detecting the trailer and sometimes reporting an issue, I am clearly using a 7-pin connector since that functionality is NOT present with a 4-pin. It is tight and latched in place by the truck connector's dust/moisture cover as it should be.
2) No, the breakaway is not pulled and the brakes release and engage with the truck's brakes as best I can tell. There is no "parasitic" power being pulled from the battery.

I have fashioned a "fake trailer" (7-pin connector and actual brake magnets, no simulated load) to do some testing without having to haul the actual 30' trailer around. Initial testing indicates that the real trailer might be at fault as I haven't yet seen any phantom trailer connection messages. Need to do extended testing to confirm, to include monitoring actual brake current during operation if I can determine how best to accomplish that. Also the weather has turned cooler and rainy--not ideal conditions for testing. Will post as I make progress.

 

[joesstripclub]

I had a similar issue when I was living in CO. First trip with a new travel trailer, went up to Taylor Park and on the way back down on the concrete section of highway the truck and trailer started porpoising bad over the joints in the road and I started getting a check trailer connection message on the screen. Made it down the mountain slowly and had the dealer pick the camper up since it was under warranty. They said one of the trailer brake wires had come loose and was shorting out. If you have narrowed it down to your trailer it might be something to check.

 

[Loudram]

Did you find the problem? If not, you might want to check the connection behind the bumper where the wiring harness plugs into the back of the 7 pin connector.

 

[tgrfan2]

MY 2026 does detect the 4 pin. I have one of those light strips below the tailgate. The truck gave me a warning one day and sure enough the right side turn signal on the strip wasn't working. The 4 pin was loose. Also, when the strip is connected, the rear sensors won't work because the truck detects a trailer is connected. Maybe yours is different if you don't have parking sensors.