isuhunter

I have a 2010 F150 and about a year ago had a topper installed. Around the time the topper was installed I lost running lights on the trailer. Yesterday I finally had some time to take a look at it. (I don't think the topper is the issue)

I do have strong continuity from the harness plug at the hitch to the next plug on the frame of the truck. At that plug (plug on frame above spare) I do not have power to running lights, however I still have tail lights, from what I can tell they run off the same wire, correct?

The plug I'm referring to is at the S400/S401 on this picture.

raisin

I assume you know there are different fuses for truck lights and trailer lights.

isuhunter

Yeah we looked there.

kidastra

iTrader: (1)

Need more info. Running lights/park lights are basically the side markers and dim brake lights. When you say tail lights do you mean brake lights or the dim lights and side markers. Also are you talking about the 7pin or 4pin.


4pin wire colors are yellow - left turn, green - right turn, brown - running, white - ground Running lights will run off the brown wire. Brakes and turns will run off the yellow and green.

Check fuse 67 under the hood that's for the park lamps
73 under the hood trailer stop/turn lights


Could also be a relay 6 under the hood is park lights
37 + 38 left and right turn/stop

isuhunter

Both 4 pin and 7 pin are doing this.

When I say running lights I'm referring to when my lights are on I don't get any lights on the trailer, if I turn on a signal or a brake I do get lights on the trailer.

I'll double check the relays again.

kidastra

iTrader: (1)

Ok so you need to focus on the brown wire, park lights system

Fuse 67
Relay 6
Both under the hood

isuhunter

Awesome I will take a look again tonight.

kidastra

iTrader: (1)

any progress?

isuhunter

I don't have a number 67...

ROBFX4

I had exact same problem. Finally found the burnt fuse not sure what number.
Mine burnt when I was hooking up the boat in the dark I stuck the plug in upside down and burnt a fuse.