Troubleshooting 2012 Ford F-250 with No Trailer Running Lights, Fuse Good

Question:

Have a 2012 F250. I have no running lights to the plug for the trailer. All other lights work fine. Go to the fuse box under the hood and the fuse is fine checked with Multi Meter. Checked the prongs in the fuse box and it does not appear that I am getting power to the fuse. There is also a relay for the trailer running lights in the same box, however I do not know how to check to see if this relay is good or bad. Also, would the power go to the relay then the fuse or the fuse then the relay? Thanks for any help.

asked by: Pat T

Expert Reply:

The easiest way to test a relay is to substitute it with a known working relay and then see if the circuit then starts to work. I would almost guarantee this is your problem based on what you described.

Most likely the power would go to the relays and then to the fuses since the relays are what power the circuit and the fuse is what protects the circuit. A relay can go out without blowing a fuse though in case you were wondering if your fuse being good was an indicator of the relay still being good.

Since you said the fuse is good but there is no power to the circuit that would seem like a dead giveaway that the relay is at fault.

expert reply by: Jameson C

Danny G.

3/11/2020

on my 2012 f250 my running lights dose not work but my break lights and blinkers do work where is the fuse for that

Chris R.

3/12/2020

On your 2012 F-250 you will want to check the 30 amp cartridge fuse located in the # 26 position inside the power distribution box under the hood.

Bryan R.

5/26/2022

@ChrisR thank you for the answer. Ill check it out.

David

8/5/2020

My 2012 f250 has no power on the control side of the relay for the trailer running lights. I have a good ground all fuses intact. I'm thinking body controller fault to the relay.

Chris R.

8/14/2020

If you're able to test for power before the module but don't show any on that circuit after it, then it's definitely a bad module. If this is a factory harness you'll want to take the truck up to a local Ford dealer.