No Running lights, no brake lights or signals on 5th wheel!

[efhole]

Seasons Greetings!
Hopefully someone can give me some insight to my issue. I was traveling home from a recent trip to the beach in my 5th wheel, when it began getting dark (was almost home). As I was driving, I noticed that I didn't see any marker lights burning. When I pulled over, I checked everything and none of my marker lights worked. Additionally, I had no turn signals or break lights, but did have breaking power with my controller. Can someone guide me as to where I need to look for the issues? Thanks in advance!

 

[halfwright]

I would use a test light at the trailer plug on the pickup to isolate the vehicle. If you got power there, it is in the trailer--otherwise in the p/u.  Most commonly, it is the trailer plug from my experience. A link to diagrams

http://www.etrailer.com/faq-wiring.aspx

 

[Rene T]

If the plug is mounted under your rear bumper, it's a good chance that moisture got in there and over time, corrosion did it's thing.  That's where I would start first

 

[WA5JML]

You might check the ground connection at the plug where the pigtale plugs into the truck.  Is your connector a 7 pin flat (RV) or one of the other configurations?  Take a small screwdriver and add a little tension to the connector blades if it is a 7 pin flat.

 

[JeffPax]

If the plug is good, bad/loose ground or blown fuse/s in the trailer.

 

[Trailer traveler]

I believe there is only one ground in the 7 pin plug, so if the breaks are working, you have at least some grounding of the system. You did not say whether the lights on the truck were working? If they are and you have a volt meter, or even a test light, try each circuit on the truck side of the 7 pin. If you can't get current there then it may be a fuse or a problem in the harness coming to the 7 pin connector. If you have power at the truck side,  I would start by cleaning the contacts on both plugs. A point file or emery board trimmed to fit works pretty well for this. Also try spreading the connectors as someone else described.

Good Luck!!

 

[driftless shifter]

Generally when all lights fail( I'm assuming tail lights are included in the marker lights circuit) it's the ground. Electric brakes may be grounded before the break in the ground wire or get enough ground through the hitch. crawl under the trailer and look for harness bundle that may have snagged road debris and definitely check the plug internally for corrosion.

 

[efhole]

Thanks for all the replies. Yes, it is a 7 pin plug and yes, all the lights on the truck work. At this point, I will test the connections and see if I can't isolate whether the issue is at the truck or at the trailer.

 

[Marsha/CA]

Also check the fuse panel in the truck, usually under the dash.  I had a horse trailer that did the exact same thing and it was the fuse marked "auxiliary".  Replaced the fuse and all the trailer lights worked again. 

Marsha~

 

[Old Blevins]

All excellent answers, IMHO.  My money's on Marsha's suggestion (fuse panel in truck) due to the fact that the trailer brakes are working (suggesting the ground is probably okay), and all the trailer lights are not working at the same time.  If it were just some of 'em, I'd say plug connection, but all of the connections for just the lights and not the brakes failing at the same time suggests to me the truck fuse.  Halfwright's suggestion of using a test light at the truck end of the connection is sure where I'd start.

Of course, one wonders what made the truck fuse go, but that's for later...

 

[Wigpro]

I had problems with mine when replacing the plug which was rusted and corroded...after taking the old plug off and putting the new plug on somehow I lost power...on my Ford there is a separate fuse box under the hood that is specifically for the tow package and they are those tiny little blade fuses and sure enough one was blown...must have shorted something out while putting on the new plug, but it drove me crazy for about an hour...

I used a small test light and checked each wire...grounding to the frame of the truck....

Good Luck...

Jim

 

[Rene T]

EFHOLE,
How did you make out? Did you resolve your issue? Another thing you could try is hook up your trailer to another truck or your truck to another trailer. That would isolate it at least.

 

[carey965]

i had a similar problem with my f150, the tabs on the 7 pin got corroded, you can buy a whole new receptacle for less then 20 bucks that plugs in to the factory harness

 

[dizz49]

I don't know why, but I found out by experience that the trailer lights on my keystone will not work if the trailer batteries are dead.

 

[efhole]

Maybe someone can give me a few pointers on this, but I am currently at a campground (store my 5th wheel here) for the first time this year and am plugged in and set up. I just purchased a continuity tester to see if I had juice at my 7 pin trailer plug. Not sure if I'm doing it right or not, but I'm grounding the lead end on the 5th wheel hitch and probing each slot on my 7 pin and none of them are showing juice. I am plugged in at the campsite, so what am I missing here?  :-\

 

[Rene T]

You should get power to only one of the pins. It's the one that goes to your RV battery. You have to check the pins on the tow vehicle. Those pins is what sends power to your trailer lights.

 

[efhole]

OK, makes sense. Do I test the pins on the tow vehicle the same way?

 

[Rene T]

Do you know someone with a tow vehicle and a seven pin receptacle? If you do, have them hook up to your trailer electrically and see if everything works in your RV. At the same time do you know anyone with a RV that you could hook up to. That's the easiest thing to do right now.

 

[falconhunter]

Before you plug another truck to your camper you need to do a little more testing. If your trailer has a short you are just going to blow fuses in their truck and it's not going to tell you anything. If your not sure how to troubleshoot the system, your better off finding a friend or fellow camper to help you out. Most campers with this knowledge will be happy to help you. It's very easy to troubleshoot if you know what your doing and a few quick tests will diagnose the problem. With that said, finding the problem or short after diagnosis can be a little tricky. Wires can get pinched anywhere and rodents can cause shorts while the rig is stored and grounds can rust or corrode.
If you find that the fuses are blown on the truck you have to find the short or problem on the trailer that caused it. Here is a quick search that has a couple utube videos of how to test it out.
https://www.google.com/search?sourceid=ie7&q=testing+a+7+pin+trailer+plug&rls=com.microsoft:en-US:IE-Address&ie=UTF-8&oe=UTF-8&rlz=1I7TSND_enUS484US484

 

[hoddinron]

Have had this problem on two different trailers.  A tag along, and our current 5th Wheel.  Each time it was a blown fuse in the truck.  Under the hood, and well marked.  I started carrying extra fuses on the first truck, and also never connected the 7 pin while the truck was running. 

On the current truck the fuse was different (larger and more expensive) and the cause of the blown fuses was a short in the front marker lights.  Disconnecting the marker lights kept me going on an 11,000 mile trip last summer.  After I got home the wires to the marker lights were replaced and everything works fine now.

Ron