Trailer side marker lights

[brettcm]

Hello.

I have a fairly new problem. I have a 2010 ram 1500 that when I remote start it the side marker lights on the trailer come on but as soon as I put the keys in and turn it on they turn off and do not come back on when I turn the headlights on. I'm the original owner of the truck and have never had this problem before on past trailers. I can turn the truck off and remote start it again and they will come on again so I've ruled out any wiring problems with the trailer. When using 7 pin tester during remote start everything is good but when the key is in I get nothing for the side markers.

 

[62Blazer]

So you don't have any taillights either? The side marker lights and the taillights are usually wired together. I've never seen a 7 way that has separate tailights and side marker connections.

 

[04fxdwgi]

Tail lights and side marker lights are the same thing.

 

[62Blazer]

Tail lights and side marker lights are the same thing.

View attachment 574877

Yep, exactly. That's why I'm confused and asked the question about the taillights.

 

[Marshall]

First thing I would look at is all the wires, starting under the truck.
At this age , I would expect to see road damage, water, salt corrosion, same with the trailer.
I would think current leakage thro corroded insulation, connectors, joints.
You start ruling out wiring problems with the trailer is usually where the problem will be.
if you have marker lights ,but no tail lights , that is a huge red flag.
Every trailer I have had always had crappy wiring, usually out with no protection

 

[04fxdwgi]

Again, he hasn't answered if the tail lights are also not working. His only ask was about side marker lights.
If the tails do not work, there may be a problem with the BCM programming or a bad TIPM.

If the tails do work, then it's a trailer wiring problem, for sure. Maybe he has a bad ground between the trailer and the truck.

When I added the OEM trailer controller on my truck when I got it, I found options in the BCM using the AlfaOBD that had the trailer tail lights relay turned off in the TIPM. Trailer brake lights were turned off, also. Very strange