Trailer running lights always on

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Joined
Jul 2, 2020
Posts
62
Reaction score
52
Location
Las Vegas
Ram Year
2018
Engine
Cummins 6.7
My trailer running lights are on permanently. I checked the F29 fuse, and it is good, when I pull it, the power goes out, so the fuse is good. I suspect the relay is frozen, but can't for the life of me figure out where the relay is, Googling only shows me 2004 and under where you have to remove and take apart the fuse box, I hope it's changed since then. The wiring diagram calls it the "Relay - Trailer tow park lamp", and is on a brown wire out of the Power Distribution Center (W756). On the 7-way, it is the top left connector. This should only be energized when the truck lights are on (hence, my suspicion that the relay is frozen closed, because mine is energized at all times, even with the ignition off).

Any help?

First post here, I'm desperate, but happy to join the community. I only bought the truck 2 weeks ago, and love it so far besides this.

Thanks,
David
 

crash68

ACME product engineer
Staff member
Administrator
Supporting Member
Joined
Mar 20, 2016
Posts
10,704
Reaction score
16,709
Ram Year
2015
Engine
3.0 EcoDiesel
The relay is built into the Power Distribution Module (fuse panel).
You might want to check the wiring to the BCM. Keep in mind that the circuit is grounded through the BCM, that's how the circuit is controlled
 

Attachments

  • TRAILER-TOW-SYSTEM.pdf
    334.8 KB · Views: 34

josheras

Junior Member
Joined
Oct 2, 2022
Posts
1
Reaction score
0
Location
florida
Ram Year
2018
Engine
hemi 5.7
where is to find the diagram electric for 18 ram 1500 sport hemi 5.7?. I have a problem with the 7 blade connector plug. When I applied brakes the running lights blade on in the connector.
 

18CrewDually

Senior Member
Joined
Nov 17, 2019
Posts
2,012
Reaction score
2,584
Location
U.S.- New Jersey
Ram Year
2018
Engine
Cummins 6.7 H.O.
Is your trailer wired correctly? The top 2 terminals are 12v charge and Parking lights. If the wires are crossed or touching inside the trailer plug the parking lights on the trailer will illuminate.
7-way.jpg
 
Top