No Trailer Running Lights Troubleshooting on a 2012 Dodge Ram 3500

Updated 04/23/2013 | Published 04/21/2013

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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

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Question:

I have a 2012 dodge ram 3500 dually. I had it hooked to a horse trailer which has worked perfectly -all lights. After being hooked for three consecutive days one running light was flickering - then suddenly no running lights but turn signals and brake lights ok. I switched to my other trailer which normally works perfectly and same behavior - no running lights but all others ok. Checked fuses - no fuses appeared blown. I also had a head light on the truck with a loose wire connecting it that made the light not work. Headlight is ok now but trailer behavior on both horse trailers identical both trailers used 10,000 miles a month.

asked by: Athena H

Expert Reply:

It sounds like you have narrowed the problem down to being on your 2012 Dodge Ram 3500 since multiple trailers have had the same results when connected to that vehicle.

It sounds like the problem could be a blown relay on your truck since you have checked the fuses. However, the fuse you would be looking for should be in cavity J14 and will require a 20 amp cartridge fuse.

We have seen this issue a few times and have seen some threads on the internet where people have had this problem and it was just a matter of replacing the fuse or in some cases the relay, but we have also seen situations where even after all of that was replaced the running lights still would not activate on the trailer.

If you cannot track down the problem you might be interested in hardwiring in a 4-way part # C58044 to give you a 4-way and then use a 7-way installation kit # ETBC7 to have a functioning 7-way.

expert reply by: Jameson C