trailer lights aways on- resolution

[canonsue]

Hi Friends,
I just picked up my new Little Guy trailer and noticed that I have a problem. The trailer lights are always on when plugged into the truck. They are on when the truck lights are off and the key is out.

Since I have never towed a trailer with this truck, I need to figure out if it is a problem with the truck or the trailer. Has anyone had this problem? What suggestions do you have for troubleshooting this issue?

Thanks,

-Sue

[Gage]

Who installed the plugs on both the truck and trailer? Most likely the plug on the truck is wired wrong.

[canonsue]

Hi Gage,
It is a new 2011 Ford F-150. The towing package came with the truck, so Ford wired it. I installed the relay and fuse for the trailer. Maybe a bad relay?

Could it be a trailer wiring issue?

Let me ask this question. When the key is out and the truck lights are off should there be no power going to any of the pins in the trailer plug?

Thanks,

-Sue

[eamarquardt]

Sounds like the trailer and tow vehicle aren't wired the same. Perhaps the battery lead from the tow vehicle is wired to the lights on the trailer.

I'd see how the lights work with the tow vehicle lights turned on, the emergency blinkers on, and the brakes operated. Then you'd be able to get a better feel for what is going on.

Cheers,

Gus

[Gage]

Hi Gage,
It is a new 2011 Ford F-150. The towing package came with the truck, so Ford wired it. I installed the relay and fuse for the trailer. Maybe a bad relay?
If it sounds like a truck issue, I can take it to the dealer without cost for a fix.
Anyone else have any ideas?
Thanks,
-Sue

If you can take it back to the dealer at no cost, that's what I would do. It's most likely something real simple. Do the turn signals and break lights work ok? Do you have a test light you can poke in the socket that the tail lights work off of. That wire is most likely hooked up wrong. Then again the relay box may be hooked up wrong. Like I say, probably something very simple.

[Miriam C.]

A good dealer would be more than happy to look at the issue of the truck and maybe even the trailer together. I would take it to them first....What you don't want is to mess up that new truck and if the lights are off but you have lights on your truck is wired wrong.

There is no way for the trailer to draw power where there is none. I think

[proformance]

Go to an RV supply (some auto parts stores will also stock them) and purchase an LED Trailer Socket Test. The unit plugs strait into the tow vehicle receptacle and will identify any problems with the vehicles wiring.

I would think there should be no power to the trailer with the vehicle not-running and all run and headlamps off.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=380323367474&viewitem=

-or-

http://compare.ebay.com/future/280638844445?var=svip&sort=BestMatch

I would try to evaluate it myself before hassling with the amount of time the dealer is going to cost you. I stay away from dealers if I can. They always want your vehicle for a day or two.

[Miriam C.]

A brand new truck! The dealer should be happy to check it out without charge and if they took it to U-haul like my dealer did U-haul guarantees their work too...It should be covered under the bumper to bumper.

[canonsue]

Yes, I am sure that the dealer will do it without charge but I agree with proformance, it may not be quick. I am going try a new relay as that is what I think may be the problem. I will call the dealer first just to see if they can do a quick circuit test and install a new relay quickly. if not, I will buy one and put in myself and see if that will fix the problem.

Sue

[mvperini]

question, is your truck trailer connection a 7 point plug, if so you may have your trailer taillight wire pluged into the battery wire coming from the truck.





Mike

[High Desert]

One of the plugs has the tail light wire connected to the wrong pole. Could easily and even more likely be the trailer, as the Ford would be done with a factory harness. The pickup probably has one pole hot all the time for charging a battery on a trailer and that is crossed with the tail light wire in either the trailer plug or pickup receptical. Either way, it should be an easy fix for someone that knows what they're doing. Seen this before. Good luck with it

[Nitetimes]

Years of experience dealing with these issues tells me that the trailer charge and parking light wires are in the wrong holes. There is no way for them to wire the truck wrong....all the wires for the tow package are molded in to their respective plugs, including the trailer plug. It's just plug and play. So unless you got that 1 in 1 million that happened to get screwed up you need to take the trailer to the dealer and have them check their wiring. On another note, taking it to the Ford dealer for trailer wiring will rarely result in the desired outcome. I worked for a trailer manufacturer for 20 years and calling any of the major dealers was generally a waste of time, they know very little about the trailer wiring. (no, not just Ford, all of the manufacturers, it's not something they are really trained on) Trailer problems are generally more easily solved at a trailer manufacturer/sales place that has a service department.

[Nitetimes]

Ya beat me by....that's about how long it took me to type that.....,Shaun!

[proformance]

question, is your truck trailer connection a 7 point plug, if so you may have your trailer taillight wire plugged into the battery wire coming from the truck.

Mike

I thought about this too, but on Fords, the battery charge for the trailer is run through a relay and only activated with ignition. So if the ignition is off, and all lights are off, and we assume the tow vehicle is wired correctly with no bad relays, the source of the 12V must be the trailer battery (if the trailer has a battery).

Meaning, the trailer is not wired per industry standards, or there is a short in the trailer wiring. If either of these is true, it is very possible the trailer battery is back feeding through the tow vehicle wiring, returning to the trailer lights.

Here is a link to proper "SAE" (Standards for Automotive Engineering) Trailer Wiring.


http://rvbasics.com/techtips/rv-travel-trailer-plug-wiring.html

-and-

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

[john warren]

is that a seven prong? on may stay hot for battery charging?

if so its your problem. could be your ground is bad and its feeding back threw the system.