running lights on trailer do not work, all other lights work stop and turn

If the truck light,s are working,i think it may be a bad pigtail,and or wiring,the same fuse that run,s the tail ,and brake light,s run the trailer.

Gahesson did you ever get a response to your question, am having the same problem with a 2014 f350. Can’t pull out the problem, all fuses test good, no power to 3 trailer hookups on the parking lights, stop and turn good.

Not yet

Had a 2015 f-250 would blow a fuse every time you connect a trailer unless you turn the running lights off of auto when you plug it in, Was going out of town tonight with my 2017 f- 250 and no trailer lights, found a blown fuse 30amp number 99 and no auto parts carry it in stock. my brother in law just had the same problem with his on the way to Alaska from Florida had to find a dealer to fix the fuse,

I had the same problem, stop and signal lights work, no running lights on trailer. Pulled fuse panel on 2002 Ford F-250 and checked fuse number 6 that go to trailer stop and signal light and it was good, still no voltage to brown wire on trailer hookup. Finally found that fuse number 38 was blown, replaced, now voltage on brown wire, but still no trailer running lights. Checked brown wire on trailer back to rear of trailer, no voltage. Replaced brown wire, now have running lights. Hope this helps. Turned out to be multiple problems.

2016 Super Duty have no power to the flat plug running lights got turn signals and brake lights on the trailer check the fuse panel for 30 and it checks good with a meter running lights on truck work help please

Got same problem. No running lights on 2014 Super Duty or Trailer but brake and turn signals work fine.

have a 2010 F250 super duty with no power on trailer plug. Checked all fuses, swapped relays still no power at plug. I had one blown fuse No, 33 replace still no power. are there any inline fuses from the factory brake controller I could look for. I'm lost.

not sure if all know that the trailer fuse panel is usually under the hood in engine compartment....also common culprit is trailer plug connectors at harness above rear bumper.

I have a 2019 F-250 and all lights work on truck and blinker and brake lights work on the trailer but running lights don't work on the trailer. I have no power on running light plug on bumper. Any help would be greatly appreciated

Here is the latest from our Ford technician which sounds like a crock to us, however, we had the same problem with our trailers. Trailer lights all in working order, plug into truck, no lights. Ford says, "Fuse (#90) is designed to fail if trailer is plugged in with vehichle and/or lights on." .... seriously? What if it's pitch black out?? Anyway, that's the "official" answer.

GuruK939B.... did you ever figure it out? We have a 19 F350 with the exact same thing. I found fuse “99” blown. Replaced it and the lights worked. I went out last night to drive it, and same problem again. I’m going to look at it today. I have pulled the trailer with other trucks, no issues. So, I don’t think the problem is with the trailer. Shoot me a email... bknable@gmail.com

Did anyone smell burning wires inside the truck. My 2019 3 month old 250 Ford Super Duty had the fuse 99 fail 13 times with 5 different trailers the same problem running lights not working on the trailer the dealer says it’s the trailer at that time it failed on 4 trailers went to California this weekend burnt 3 more fuses now it’s 5 trailers did you smell burnt wires?

Same thing on my 2018 F-250 running lights are out and I checked several fuses and found the number 99 in the back of main fuse box blown about the first time in my life I over 55 years I had a fuse blown for trailer running lights brand new trailers . Like one guy said if it's not grounding good or you plug in with lights on it will blow

2010 F250 diesel running lights don’t work. Pulling a trailer and all existing lights in trailer and truck work fine.... any ideas?

2015 f-450 trailer running lights were not working only turn, brake and emergency lights, after checking a few fuses found #26 blown on main box, replaced it and everything is back to normal again.

2012 F350. Same problem, brake lights and turn signals work fine but no running lights. Replaced 30A cartridge fuse for “trailer tow park lamps”, fuse #26 in hood fuse box. Problem solved!

Same problem on my 2016, F250 (6.7L diesel). After checking for obvious fuses and relays, I discovered that I was missing a fuse, yes a missing fuse, at the Power Distribution Box, in the engine compartment. I was missing fuse #26, (a 30-amp fuse), so I bought me a $6.00 fuse, plugged it in and LIGHTS. Horse trailer lit up like a Christmas tree. I purchased this truck new so I'm pretty sure I'm the only person that's been in the Distribution Box, and that was once or twice, and I don't recall removing any fuses. The question is: Did they forget to install the fuse at the factory? Regardless, installing my own fuse FIXED the problem immediately. Note: Fuse #26 is labeled, "Trailer tow park lamps", in the Ford owner's manual, page 224. There is no mention of Running Lights but that's the fuse you need to check. Note: In addition to the fuse, there is a relay, (relay #29) being utilized in this lighting circuit. You may have to replace the relay if the fuse is good.

Just want to share mine also. I have a 2017 Ford F-250 6.7l Diesel. Plugged in my trailer and only Brake's and Blinkers. Mine was fuse 99 blown. Swapped out and problem fixed!

My 2017 F250 had same problem no running lights on trailer. I checked fuse 99 and it was bad. Thanks everyone for the help

I have a 2020 f250 6.7 and all the fuse are there and check out good but no running lights and my fuse panel stops at 70 spots.. not really looking forward on taking it in to Ford and the truck being a week old.

Symptom: GMC 2019 Sierra when attached to 16-foot Cargo trailer (20 years old), the running lights come on for 1 second then shut off. If you turn the headlights off and on again, the come on again for 1 second and go off. The dealer could not fix this. GMC corporate was no help. It’s taken 2 years to figure this out. Trailer lights work perfectly when attached to 2017 GMC Yukon. 2019 Sierra powers new trailers just fine. This has nothing to do with the software upgrade for the trailer app build into the 2019 Sierra. Dealer did that and it made no difference. Even replaced trailer receptacle on truck….no difference. Solution: The issue has to do with the total wattage load of the running lights. The trailer app shuts down the lights if the total wattage is too great. Even my medium size trailer has 18 running lights ( 36 bulbs) around the trailer. Found this out by temporarily disconnecting half of them and the then plugged it into the truck. I replaced 10 incandescent bulbs with LED bulbs, and the problem is finally solved! There is no GMC guidance, rating, or warning about this.

2020 Super Duty trailer running lights is #10 in under hood fuse block, 30 amp.

2015 F 250 FX4, No running lights on my trailer, and so after reading this I started thru the PDC. #26 slot, a 30 amp fuse was blown, and after replacement, I now have power to the pin designated for the running lights. Thanks guys.

Hello All, Good so see i'm not the only one with issues. So my problem is I have all my lights working however my trailer BRAKES are not and i'm trying to take a trip in two days and I work all day tomorrow ;( 2013 F250 6.7

@Wilson6391 Did you ever get it figured out? 2020 F350 6.7 SD here, same issue.