Brake lights work no taillights

[BlessedGirlie]

Just pulling out from a great weekend of camping in NC. It's raining 😢
we notice our trailer lights arnt on.
The brake lights work and signal lights. Don't see an exterior trailer fuse in the box.
At least we r traveling in the day time😳
Any suggestions? Driving a F250
Did I mention it's 46 degrees and raining? #goodgrief

[bedrck46]

What year is the F250?


I suspect that you have a blown fuse Check in your owners manual and look for the Trailer Running Lamp relay or something that may be worded similar depending on the year the F250 is there should be a fuse associated with that relay

[Mustang65]

Originally Posted by BlessedGirlie

Just pulling out from a great weekend of camping in NC. It's raining ��
we notice our trailer lights arnt on.
The brake lights work and signal lights. Don't see an exterior trailer fuse in the box.

Do you have a Volt/Ohm meter? If not head over to Wallmart and pick one up. One of the best tools you can have.

There are 2 ways to look at this.. from the TV end or from the TT end. Lets start from the easy end the TV (F150 side). Start the engine, turn on the running lights and take the volt/ohm meter set to DC VOLTS. Put the Black lead into the ground connector of the plug and the RED lead into the "Markers" lights (running lights) connector. You should see 12 - 14VDC. If you do, the voltage is leaving the F150 ok. See below picture for pin-outs.

If you have 12VDC at the TV's connector let us know and I will go over the TT tests you need to do.

Don

[TWP723]

So you have no running lights but have brake lights? Does the truck have lights?

[BlessedGirlie]

its a 2015 250 and we think you are right Gonna relook when we get back home. That fuse box is not in an easy position to get to on a cold rainy day. Glad we are traveling in day light. Thanks for your help!

[mike837go]

In the future, as an expedient, you can jumper between the top two pins of the 7 pin connector and power the running lights directly from the battery/charging circuit.

[norty1]

The trailer light fuses on my F350 are in a box under the hood.

[BlessedGirlie]

Yes truck has lights. We feel sure it is a fuse we r about to be where we can check it. (If it will stop raining��)

[TWP723]

It's in the trailer then. Or it's a bad relay in the Smart Junction Box under the hood.

[TWP723]

Oh and btw...the relay is covered under warranty.

[Scoutr2]

Tail lights and marker lights are on the same circuit. This happened to me on my Outback and it turned out to be a short to ground on one of the marker lights. Check the fuse first. If not that, you have a short somewhere. That can be harder to trace down.

Like mike837go said - the top two (female) pins on the trailer plug are the markers/tail-lights and 12V supply. For a quick check without any meter, You can take an automotive fuse (10 amp or higher) and push into those pins (see diagram shown earlier). If your markers and tail-lights come on then, you have a problem with the truck connector or the tail-light wire from the truck to that connector.

Good luck! Hope it's just the fuse.

[RoyBraddy]

It could be a bad connection in the trailer connector that plugs into the truck. I always squirt some WD40 into the connector and move the plug around a bit in an effort to clean up the connection some.

You might want to get one of those 7-way tester adapter that has small LEDs on it. This will tell you you right away if the truck circuits is good or bad. If all the led lights are working when they are suppose to be then the problem is on the trailer side...

looks like this available from etrailer or AMAZON...


Roy Ken

[Jagiven]

Your TV might be different, but on my Dakota, I had to replace a blown fuse, in the fuse/relay box that is under the hood

[Edd505]

Originally Posted by BlessedGirlie

Yes truck has lights. We feel sure it is a fuse we r about to be where we can check it. (If it will stop raining��)

The truck has tail lights the problem is in the 7pin connection or the trailer it self. RoyBraddy's checker or a test light at the 7pin will tell if power is getting to the TT.

RoyBraddy thanks never saw one another add to my on the road kit!

[Jagiven]

A lot of people are not aware that the 7pin connector and your TV lights are not connected to the same fuse, they are isolated from each other. I found this out the hard way when I jackknifed a trailer a few years back on ice. I thought I damaged the wire harness, Dealer replaced the fuse under the hood and charged me well over $100. Luckily I billed it back to the insurance claim.

[Crabman]

Originally Posted by Jagiven

A lot of people are not aware that the 7pin connector and your TV lights are not connected to the same fuse, they are isolated from each other. I found this out the hard way when I jackknifed a trailer a few years back on ice. I thought I damaged the wire harness, Dealer replaced the fuse under the hood and charged me well over $100. Luckily I billed it back to the insurance claim.

I learned this the hard way as well. Had a boat trailer and could not get all the lights to work but the truck lights worked fine. Replaced the lights and wiring on the trailer thinking they must be defective, still nothing. Then I found the trailer light fuses on the inside of the cab fuse panel, one of them was blown. I felt pretty dumb at that point after changing the lights and wiring for nothing.

Moral of the story is the truck lights and trailer lights can have different fuses if you have the tow package, so your truck lights may be working fine even with a blown trailer light fuse.

[Camper_bob]

Originally Posted by Jagiven

A lot of people are not aware that the 7pin connector and your TV lights are not connected to the same fuse, they are isolated from each other. I found this out the hard way when I jackknifed a trailer a few years back on ice. I thought I damaged the wire harness, Dealer replaced the fuse under the hood and charged me well over $100. Luckily I billed it back to the insurance claim.

Originally Posted by Crabman

I learned this the hard way as well. Had a boat trailer and could not get all the lights to work but the truck lights worked fine. Replaced the lights and wiring on the trailer thinking they must be defective, still nothing. Then I found the trailer light fuses on the inside of the cab fuse panel, one of them was blown. I felt pretty dumb at that point after changing the lights and wiring for nothing.

Moral of the story is the truck lights and trailer lights can have different fuses if you have the tow package, so your truck lights may be working fine even with a blown trailer light fuse.

I learned this one the hard way too. First weekend we had our trailer, the wire got pinched somewhere. I brought it back to the dealer (boy was that an adventure with intermittent brakes and lights!) who replaced the cord (warranty ) and checked all the fuses on the trailer side. I went to plug into the truck, and no good on some lights. Turns out the pinched wire had shorted out the circuit and blew one of the fuses under the hood of the truck, but the truck's tail lights still worked perfectly. Tech at the RV shop popped in a new fuse for me and advised me to get some spares. So I did; now I have an assortment of fuses for the truck as well as the trailer.

[Scoutr2]

I still maintain that using an automotive fuse to connect the top two female pins on your trailer plug will confirm whether you have a problem in the trailer wiring, or the trailer connector on your truck. No meter needed for this basic check.

[dgantz]

were sort of in the same boat, 2017 Greyhawk. We have brake lights but no turn signals.
Are the pins in the attch 7 pin connector picture the same on the e450 as the f150? if not where can I get the correct picture for pin location?

[citgodan]

X2 on cleaning the trailer connection with WD-40. I had a pin not making a good connection/contact with my truck's 7 pin box before. after WD-40 issues were gone.